Success in CLS Ch. 11 UA & Body Fluids (67 q.)

What is the expected pH range of a freshly voided urine specimen?

4.5-8.0 pH is a representative symbol for the hydrogen ion concentration. The kidney plays an important role in the maintenance of the acid-base balance of body fluids by either excreting or retaining hydrogen ions. A normally functioning kidney will excrete urine with a pH between 4.5 and 8.0, depending on the overall acid-base needs of the body.

Metastatic carcinoid tumors arising from the enterochromaffin cells of the gastrointestinal tract are characterized by increased excretion of urinary

5-Hydroxyindole acetic acid The intestinal enterochromaffin cells, sometimes called the argentaffin cells, produce a substance known as serotonin from the amino acid tryptophan. In cases of metastatic carcinoid tumors, excessive amounts of serotonin are produced. Serotonin may then undergo oxidative deamination to form the metabolite 5-hydroxyindole acetic acid (5-HIAA), which is excreted in the urine. It is the quantification of 5-HIAA that is diagnostically significant because it reflects serotonin serotonin production.

If a fasting plasma glucose level of 100 mg/dL is obtained on an individual, what is the expected fasting cerebrospinal fluid (CSF) glucose level in mg/dL?

65 CSF is a clear, colorless liquid that may be described as a modified ultrafiltrate of blood. Both active transport and passive diffusion are involved in the passage of glucose from the blood into the CSF. Normally, fasting CSF glucose levels range between 50 and 80 mg/dL, representing approximately 60-70% of the blood glucose level. In hyperglycemia with plasma glucose levels of 300 mg/dL, the active transport mechanism reaches a point of maximum response, so that CSF glucose levels reflect approximately 30% of the plasma glucose level. Decreased CSF glucose levels are associated with hypoglycemia, a faulty active transport mechanism, and excess utilization of glucose by microorganisms, red or white blood cells, or the central nervous system.

Which of the following will contribute to a specimen's specific gravity if it is present in a person's urine?

85 mg/dL glucose Only dissolved solutes affect specific gravity (e.g., glucose). Cells, mucus, crystals, or any other formed elements will have no effect, regardless of concentration. If the reagent strip method is used, it should be noted that only dissolved ions will contribute to specific gravity results. Thus glucose would not affect reagent strip results at any concentration. In such instances as diabetes mellitus, with urine glucose levels over 2 g/dL, there may be a discrepancy between specific gravity results obtained with a reagent strip method versus using a refractometer, because such glucose levels are known to increase refractometer results, thus requiring correction.

A urine specimen is tested by a reagent strip test and the sulfosalicylic acid test to determine whether protein is present. The former yields a negative protein, whereas the latter results in a reading of 2+ protein. Which of the following statements best explains this difference?

A protein other than albumin must be present in the urine. When globulin, mucoprotein, or Bence Jones protein is present in a urine specimen, the reagent strip test may give a negative result because the strip is more sensitive to the presence of albumin than to the presence of other proteins in urine. However, the sulfosalicylic acid (SSA) test is able to detect not only albumin but also globulin, mucoprotein, and Bence Jones protein in a specimen. Therefore, it can be seen that a negative reagent strip test result for protein but a positive sulfosalicylic acid test result is possible when the protein present in some protein other than albumin. For this reason the sulfosalicylic acid test is run as a test for urinary protein if the presence of abnormal proteins is suspected.

The presence of ketone bodies in urine specimens may be detected by use of a reagent strip impregnated with sodium nitroprusside. This strip test is sensitive to the presence of

Acetoacetic acid and acetone Under normal metabolic conditions, the body metabolizes fat to carbon dioxide and water. With inadequate carbohydrate intake, as with dieting and starvation, or with inadequate carbohydrate metabolism, as with diabetes mellitus, there is an increased utilization of fat. Because of this increased fat metabolism, the body is unable to completely degrade the fat, resulting in a buildup of intermediary products known as ketone bodies. The term "ketone bodies" is used collectively to denote the presence of acetoacetic acid, beta-hydroxybutyric acid, and acetone. Reagent test strips impregnated with sodium nitroprusside are able to detect the presence of acetoacetic acid and acetone in the urine specimens. Although beta-hydroxybutyric acid accounts for approximately 78% of the total ketones, it is not detected by the sodium nitroprusside test.

Which of the following will be characterized by an increased number of the urinary component seen in Color Plate 52?

Acute glomerulonephritis Refer to color plate 52. Erythroctes or RBCs occur in small numbers (0-2/hpf) in a normal urine. Using brightfield microscopy, unstained RBCs appear as colorless discs with an average size of 7 μm in diameter. Increased or large numbers of RBCs are commonly seen with acute glomerulonephritis, renal calculi, acute infections, and menstrual contamination. The nephrotic syndrom is characterized by heavy proteinuria, oval fat bodies, renal tubular epithelial cells, casts, and waxy and fatty casts. Biliary tract obstruction will show pale-colored stools, whereas vaginal discharge contamination may introduce increased numbers of WBCs.

The reagent test strips used for the detection of protein in urine are most reactive to

Albumin In healthy individuals the amount of protein excreted in the urine should not exceed 150 mg/24 hr. When protein is present in the urine, the colorimetric reagent test strips change color, indicating a semiquantification of the amount of protein present. Serum proteins are classified as being albumin or globulin in nature, and the type of protein excreted in the urine is dependent on the disorder present. Although the strip test is a rapid screening method for the detection of urinary protein, it must be noted that this method is more sensitive to the presence of albumin in the specimen than to the presence of globulin, Bence Jones protein, or mucoprotein.

A pleural effusion is found to have 3000 white blood cells per microliter and 5 g/dL total protein. From this it can be determined that the patient's effusion is

An exudate Effusions can be transudates or exudates, and the distinguishing characteristics are cell number and total protein. Transudates, being noninflammatory, will have low numbers of cells and less than 3 g/dL protein. This patient's results suggest she has an exudate due to the high number of cells and large amount of protein.

Nitrite in a urine specimen suggests the presence of

Bacteria Bacteria of the Enterobacter, Citrobacter, Escherichia, Proteus, Klebsiella, and Pseudomonas species produce enzymes that catalyze the reduction of nitrate, a substance normally found in urine, to nitrite. Reagent test strips have been developed that are able to detect nitrite in urine. Therefore, a positive nitrite test result is an indirect indication of the presence of bacteria in the urine specimen.

67. Which of the following is a true statement?

Bacteria introduced into a urine specimen at the time of the collection will have no immediate effect on the level of nitrite in the specimen. Renal tubular cells originate from the renal medulla or cortex. Red blood cell crenation is a phenomenon reflecting increased solute concentration (hyperosmolality) and is not caused by urine pH. Red cells will, however, lyse at high alkaline pH. The nitrite reaction requires (a) a sufficient dietary source of nitrate, (b) sufficient numbers of bacteria present in the urine, and (c) sufficient incubation time (>4 hours). Bacteria introduced at collection, even in sufficient number, will not have had sufficient incubation time to convert urine nitrate to nitrite. Pilocarpine iontophoresis is the collection method for sweat.

The following urinalysis results were obtained on a 40-year-old white male whose skin appeared yellowish during the clinical examination. Color and clarity— dark brown, clear; protein—negative; glucose—negative; blood—negative; ketones—negative; bilirubin— moderate; urobilinogen—0.2 mg/dL. These results are clinically significant in which of the following conditions?

Bile duct obstruction In the hepatic phase of bilirubin metabolism, bilirubin is conjugated with glucoronic acid to form water-soluble conjugated bilirubin. The conjugated bilirubin passes into the bile duct and on to the intestinal tract. In the intestine, it is reduced by intestinal bacteria to form urobilinogen. Bile duct obstruction is characterized by an obstruction of the flow of conjugated bilirubin into the intestinal tract to complete its metabolism. The conjugated bilirubin, which is water soluble, will be excreted by the kidney. Because bilirubin is not entering the intestines, the normal production of urobilinogen is dcreased. Therefore, the urine biochemical test will indicate a positive reagent strip test for bilirubin, positive Ictotest, and "normal" (0.2 mg/dL) urobilinogen (because there is no reagent strip pad for "negative" urobilinogen).

A reagent test strip impregnated with a diazonium salt such as diazotized 2,4-dichloroaniline may be used to determine which analyte?

Bilirubin Bilirubin is a compound that is formed as a result of hemoglobin breakdown. The majority of bilirubin in the blood is bound to albumin and is known as unconjugated bilirubin. Because unconjugated bilirubin is not water soluble, it may not be excreted in the urine. The remainder of the bilirubin in the blood has been processed by the liver. In the liver, the bilirubin is conjugated with glucuronic acid or sulfuric acid. This conjugated bilirubin is water soluble, and it is this portion that is excreted in increased amounts in the urine in some hepatic and obstructive biliary tract diseases. The presence of conjugated bilirubin in a urine specimen may be detected by the use of the reagent test strips. The test strips are impregnated with a diazonium salt, such as diazotized 2,4-dichloroaniline, which forms a purplish azobilirubin compound with bilirubin.

A urine specimen that exhibits yellow foam on being shaken should be suspected of having an increased concentration of

Bilirubin Normal urine does not foam on being shaken. However, the urine containing bilirubin will exhibit yellow foaming when the specimen is shaken. In fact, the foam test was actually the first test for bilirubin, before the development of the chemical tests. If the shaken specimen shows a white foam, increased urine protein can be suspected.

Which of the following characteristics is true for the urinary components shown in Color Plate 54?

Can also resemble cysteine crystals Uric acid crystals, as seen in color plate 54, are commonly encountered in normal acidic urine but may be observed in neutral urine and rarely in an alkaline urine, because uric acid is soluble at alkaline pH. Using brightfield microscopy, uric acid crystals appear as diamonds, cubes, barrels, rosettes, and may even have six sides and be confused with cysteine. Because they are a reflection of the excretion of purine waste products, they may be pathologically increased in cases of gout and after chemotherapy. They show birefringence (multiple colors) under plane polarized light.

Which of the following characteristics is true of the primary urinary components shown in Color Plate 53?

Consist of uromodulin protein As ssen in color plate 53, hyaline casts are the most commonly observed cast, and they consist completely of uromodulin (Tamm-Horsfall) protein. A reference urine may contain 0-2 hyaline casts per low-power field. Hyaline casts appear translucent using brightfield microscopy because they ahve a refractive index similar to urine. Phase-contrast microscopy may be used to visualize the casts better.

Which methods may be used to quantify protein in both cerebrospinal fluid and urine specimens?

Coomassie brilliant blue and trichloroacetic acid Trichloroacetic acid is a turbidimetric method used to quantify small amounts of protein, less than 100 mg/dL, in CSF and urine specimens. Coomassie brilliant blue is a colorimetric dye binding method in which protein complexes with the dye, forming a soluble blue complex. This method also exhibits the necessary sensitivity for detecting small quantities of protein. Bromcresol green is selective for albumin and is used to quantify albumin in serum. Ponceau S is used in serum protein electrophoresis methods to stain both albumin and globulins.

To determine amniotic fluid contamination with maternal urine, which of the following measurements could be used?

Creatinine concentration Because there may be technical problems associated with amniocentesis, contamination with maternal urine should be considered in evaluating specimens submitted for amniotic fluid analysis. Urinary concentrations of creatinine and urea nitrogen are anywhere from 10 to 50 times the amniotic fluid concentrations, and an increased concentration of either in the amniotic fluid would be sensitive indicators of urinary contamination. Measurements of albumin, total protein, or lactate dehydrogenase would be of little use for this purpose because their relative concentrations in urine and amniotic fluid are not predictably different. A delta absorbance at 410 nm would be used to assess the presence of bilirubin in the sample, as in assessment of erythroblastosis fetalis.

The major formed element in the high- power field shown in Color Plate 48 is most likely a

Fiber artifact Refer to color plate 48. The fringed appearance at the one end of the major formed element strongly suggests that this is a fiber artifact, most likely placed in the sample at the time of collection. Casts, taking the shape of the tubule within which they are formed, will not have such a fringed end.

"Isosthenuria" is a term applied to a series of urine specimens from the same patient that exhibit a

Fixed specific gravity of approximately 1.010 "Isosthenuria" is a term applied to a series of urine specimens that exhibit a fixed specific gravity of approximately 1.010. In isosthenuria there is little, if any, variation of the specific gravity between urine specimens from the same patient. This condition is abnormal and denotes the presence of severe renal damage in which both the diluting ability and the concentrating ability of the kidneys have been severely affected.

The following urinalysis biochemical results were obtained from a 4-month-old infant who experienced vomiting and diarrhea after milk ingestion and failed to gain weight: pH—6; protein—negative; glucose—negative; ketone—negative; bilirubin—negative; Clinitest®—2+. These results are clinically significant in which of the following disorders?

Galactosemia Galactosemia, an inborn error of metabolism, is characterized by the inability to metabolize galactose, a monosaccharide that is contained in milk as a constituent of the disaccharide lactose. Thus galactose appears in elevelated levels in the blood and urine. The condition may result in liver disease, mental retardation, and cataract formation if not treated or controlled. In the biochemical analysis of the urine, the conflicting results for the two glucose tests may be explained as follows: The glucose oxidase reagent strip test is specific for glucose; therefore, the glucose will be negative. The Clinitest, a modification of the Benedict's test procedure, detects most reducing substances. Because galactose is present in the urine and is a reducing substance, the Clinitest is positive.

Alkaptonuria, a rare hereditary disease, is characterized by the urinary excretion of

Homogentisic acid Alkaptonuria is a rare hereditary disease that is characterized by excessive urinary excretion of homogentisic acid. This acid, the product of phenylalanine and tyrosine metabolism, accumulates in urine because of the deficiency in the enzyme homogentisic acid oxidase, which normally catalyzes the oxidation of homogentisic acid to maleyl acetoacetic acid. Urine containing homogentisic acid turns black on standing because of an oxidative process; thus the screening test for alkaptonuria consists of the detection of a black coloration in urine that is left standing at room temperature for 24 hours.

A 13-year-old ice skater is having her routine physical before the school year. Her first morning urinalysis results include color = straw; appearance = hazy; pH = 6.0; protein = trace; a representative microscopic high-power field is shown in Color Plate 50. All other chemical results were normal. The major formed elements are and suggest.

Hyaline casts and mucus; normal The major formed elements in color plate 50 are hyaline casts and mucus fibers, which are normal in the numbers shown in this field. Waxy casts will appear yellowish with characteristic serrated edges. There are no obvious granules in the casts shown, and red blood cells are not present.

Which of the following statements pertains to screening methods used to determine pregnancy?

Immunoassays will use reagent anti-hCG to react with patient hCG. Many simplified yet immunologically sophisticated methods exist currently for determining pregnancy. All are based on the reaction between patient human chorionic gonadotropin (hCG) and anti-hCG. Most kits will use an antibody recognizing one subunit of hCG (alpha or beta), whereas other kits may use both anti-α-hCG and anti-β-hCG. Internal controls in these kits will only check if the procedural steps were performed correctly. They cannot detect problems with any preanalytical variables, like specimen handling or appropriateness. In addition, internal quality control cannot be used to assess the kit's accuracy in distinguishing "positive" from "negative" specimens. Only the use of external quality control specimens can accomplish this. Because the first morning specimen is the most concentrated of the day, it is the preferred specimen for such screenings. Use of a random urine may be too dilute to detect low levels of patient hCG, thus giving a false negative.

Patients with diabetes insipidus tend to produce urine in ________ volume with ________ specific gravity.

Increased; decreased Diabetes insipidus is caused by a deficiency in antidiuretic hormone. Such deficiencies will result in the kidney's inability to reabsorb water at the distal and collecting tubules. This affects only water reabsorption and the the reabsorption of other urinary solutes. Excreted solute amounts will be the same, but the water volume into which they are excreted will be larger. This results in high urine volumes and low final solute concentrations. The low solute will lead to low specific gravities in these patients' specimens.

Some clinical conditions are characterized by unique urinalysis result patterns. Which of the following shows such a relationship?

Intensive dieting: increased ketones, negative glucose Because of increased lipid metabolism in long-term, intensive dieting, ketone body formation will increase. Blood glucose levels in such patients will be normal or decreased. In nephrotic syndrome, the large amounts of albumin excreted will be detectable by both reagent strip and SSA methods. In multiple myeloma, however, the increased globulin light chains (Bence Jones proteins) excreted will only be detectable by SSA because the reagent strip is more sensitive to albumin. Cystitis is a lower UTI affecting the bladder by not the kidney itself. This infection will not exhibit increased protein, whereas an upper UTI will.

Phenylketonuria may be characterized by which of the following statements?

It may cause brain damage if untreated. Phenylketonuria is inherited as an autosomal recessive trait that manifests itself in the homozygous form. The basis for the disease lies in the fact that the enzyme phenylalanine hydroxylase, which is needed for the conversion of phenylalanine to tyrosine, is absent. Because of this enzyme deficiency, phenylalanine levels rise in the blood, with increased amount of phenylpyruvic acid and other derivatives being excreted in the urine. If the disease is detected at an early stage, mental retardation may be avoided by restricting the dietary intake of phenylalanine.

Which of the following is characteristic of an exudate effusion?

Leukocyte count >1000/uL Effusions result from an imbalance of the flow of body fluids. Effusions are classified as exudates or transudates on the basis of certain characteristics. Exudates are generally formed in response to inflammation or infection with concomitant capillary wall damage. Exudates are characterized by protein levels greater than 3.0 g/dL, leukocyte counts greater than 1000/μL, and the presence of a sufficient amount of fibrinogen to cause clotting. In contrast, transudates are characterized by protein levels less than 3.0 g/dL, leukocyte counts less than 300/μL, and the absence of fibrinogen. Transudates are generally formed as the result of noninflammatory processes, including alterations in plasma oncotic pressure, pleural capullary hydrostatic pressure, or intrapleural pressure.

Which substance found in urinary sediment is more easily distinguished by use of polarized microscopy?

Lipids Fatty materials in urinary sediment may be identified by means of staining techniques using Sudan III and oil red O or by means of polarized microscopy. Polarized microscopy is especially useful when the composition of fatty casts, fatty droplets, or oval fat bodies is primarily cholesterol. When cholesterol molecules are exposed to polarized microscopy, the effect is such that a Maltese cross formation becomes visible, simplifying the identification process. Casts and RBCs may be better visualized using phase-contrast microscopy. Ketone bodies will be soluble and, therefore, not seen in a urine sediment.

A 22-year-old female clinical laboratory student performs a urinalysis on her own urine as part of a lab class. Significant results include: color = yellow; appearance = cloudy; pH = 7.5; nitrite = positive; leukocyte esterase - 2+; 25^0 WBC/hpf; 0-3 RBC/hpf; 2-5 squamous epithelial cells/hpf; moderate bacteria. All other chemistries and microscopic results were normal. These findings suggest

Lower urinary tract infection This student has a lower UTI, also known as cystitis. The major distinguishing features between upper and lower UTI include the presence of protein and casts in an upper UTI and not in a lower UTI. This is because both urine protein excretion and cast formation reflect what is happening within the kidney itself. The most common source of either upper or lower UTIs is contamination by enteric gram-negative bacteria. Their presence will not be found in glomerulonephritis or with urinary stones (nephro = "kidney" + lith = "stone").

Which is true about the formed element shown in Color Plate 47?

May be found in normal alkaline urine Normal alkaline (or neutral) urine may contain tripe phosphate crystals, as seen in color plate 47. These crystals can be identified by the characteristic "coffin lid" appearance. They usually do not indicate any pathology.

In certain malignant disorders, what substance is found in the urine that turns the urine dark brown or black on exposure of the urine to air?

Melanin, a substance derived from tyrosine, is responsible for the pigmentation of the eyes, skin, and hair. In some malignancies, known as melanomas, the tumor or mole takes on a darkly pigmented appearance because of the melanin present. In cases of metastatic melanoma, melanogen, which is a colorless precursor of melanin, is excreted in the urine. If the urine is allowed to stand at room temperature for 24 hours, the melanogen is oxidized to melanin, imparting a dark brown or black coloration to the specimen. Qualitative screening tests for the detection of melanin in urine use ferric chloride or sodium nitroprusside as the oxidation reagent systems.

A random urine is collected from a patient and the results obtained are as follows: urine albumin = 16 mg/dL and urine creatinine = 140mg/dL. These findings are consistent with

Microalbuminuria The ratio of urine albumin to creatinine in a random specimen is commonly used to evaluate microalbuminuria, especially in patients with diabetes mellitus. This patient's ratio is 114 mg albumin per gram creatinine. The American Diabetes Association defines microalbuminuria as between 30 and 299 mg/g. Values greater than 299 mg/g would be macroalbuminuria. Nephrotic syndrome is characterized by excretion of albumin in excess of 3.5 grams per day. Patients with obstructive jaundice will usually not experience proteinuria.

Why is the first-voided morning urine specimen the most desirable specimen for routine urinalysis?

Most concentrated specimen of the day and therefore it is more likely that abnormalities will be detected. The first-voided morning urine specimen is the most desirable for chemical and microscopic analysis because it is the most concentrated specimen of the day. Protein and nitrite testing is better performed on a concentrated specimen, as are the specific gravity determination and the examination of urinary sediment. However, because of the lack of food and fluid intake during the night, glucose metabolism may be better assessed on the basis of a postprandial specimen.

Which condition is characterized by increased levels of immunoglobulins in the cerebrospinal fluid, originating from within the central nervous system and not from the general blood circulation?

Multiple sclerosis Immunoglobulins (IgGs) are normally present at less than 1 mg/dL in the CSF. Increased CSF IgG can result from increased CSF production (e.g., multiple sclerosis) or from increased transport from the blood plasma (compromised blood-brain barrier). Neither gout, erythroblastosis fetalis (isoimmunization syndrome), nor multiple myeloma produces increased CSF IgG levels.

If a urine specimen is left standing at room temperature for several hours, which of the following changes may occur?

Multiplication of bacteria Only freshly voided urine specimens should be used for urinalysis testing. If the specimen cannot be examined within 1 hour after collection, it should be refrigerated to help preserve the integrity of the specimen. When urine is left standing at room temperature for an excessive period, multiplication of bacteria will occur. The bacteria are capable of converting urea in the urine to ammonia, causing the urine to become more alkaline. Loss of carbon dioxide from the specimen will also contribute to the alkalinization of the urine. Constituents such as glucose, bilirubin, and urobilinogen will also be lost from the specimen.

The principle of the colorimetric reagent strip test for hemoglobin is based on the peroxidase activity of hemoglobin in catalyzing the oxidation of a dye with peroxide to form a colored compound. This method may yield false-positive results for the presence of hemoglobin when the urine specimen contains

Myoglobin The colorimetric reagent strip test for the detection of hemoglobin in urine utilizes a buffered test zone impregnated with a dye and organic peroxide. The peroxidase activity of hemoglobin catalyzes the oxidation of the dye with peroxide to form a colored compound. Like hemoglobin, myoglobin also has a peroxidase activity and, when present in a urine specime, myoglobin will react, yielding false-positive results. In the presence of large amount of ascorbic acid, antibiotics containing ascorbic acid as a preservative, formaldehyde, or nitrite, the urine reaction may be inhibited, causing false-negative results.

A 40-year-old female patient with a history of kidney infection is seen by her physician because she has felt lethargic for a few weeks. She has decreased frequency of urination and a bloated feeling. Physical examination shows periorbital swelling and general edema, including a swollen abdomen. Significant urinalysis results show the following: color = yellow; appearance = cloudy/frothy;specific gravity = 1.022;pH = 7.0; protein = 4+; 0-3 WBC/hpf; 0-1 RBC/hpf; 0-2 renal epithelial cells/hpf; 10-20 hyaline casts/lpf; 0-1 granular casts/lpf; 0-1 fatty casts/lpf; occasional oval fat bodies. Her serum chemistries show significantly decreased albumin, increased urea nitrogen, and increased creatinine. These findings suggest which condition?

Nephrotic syndrome Nephrotic syndrome is suggested by the increased urine protein (with serum albumin significantly decreased), the hyaline and fatty casts, and the presence of oval fat bodies. The patient's symptoms of periorbital swelling and edema reflect the loss of oncotic pressure because of the excretion of albumin. Its loss from the vascular compartment will induce plasma water movement into the tissue spaces. Glomerulonephritis will have many more RBCs, including RBC casts. Multiple myeloma will not show increased urine albumin but rather immunoglobulin light chains. Chronic renal failure will have multiple types of casts present (hyaline, granular, cellular, waxy, fatty).

With infections of the urinary system, white blood cells are frequently seen in the urine sediment. What type of white blood cell is seen the most frequently in urine sediment?

Neutrophil The majority of renal and urinary tract diseases are characterized by an increased number of neutrophilic leukocytes in the urine. To identify correctly any white blood cells present in a urine specimen, it is necessary to examine the specimen as soon as possible after collection. This is necessary because leukocytes tend to lyse easily when exposed to either hypotonic or alkaline urine.

"Glitter cell" is a term used to describe a specific type of

Neutrophil When neutrophils are exposed to hypotonic urine, their physical appearance becomes altered. Under hypotonic conditions, the neutrophils tend to swell and the cytoplasmic granules contained within the cells exhibit Brownian movement. This Brownian movement of the granules causes the neutrophilic contents to refract in such a way that the cells appear to glitter — thus the name "glitter cells."

What condition is suggested by the number of the formed element that predominates in the high-power field of Color Plate 51?

Normal sample Color plate 51 demonstrates sperm and calcium oxalate crystals. Both formed elements are found in correctly collected normal urines from either gender. Calcium oxalate seen here is the dehydrate form. The monohydrate form will appear oval or dumbbell shaped. Neither formed element is usually associated with pathology.

The formed element shown in Color Plate 49 would usually be found in the patient's urine along with which soluble biochemicals?

Ornithine and arginine The presence of cystine crystals in a patient sample is always a cause for immediate notification of the physician. Cystinuria is an autosomal recessive disorder characterizedby the inability to reabsorb the amino acids cystine, lysine, arginine, and ornithine in either the renal tubules or the intestine. Cystine will crystallize in acid pH more readily than the other amino acids. Tyrosine forms needle-shaped crystals whereas leucine will appear round and oily with concentric rings. Isoleucine and phenylalanine will not form crystals in the urine. Acetoacetate and β-hydroxybutyric acid are two ketone bodies that will be soluble in the sample and give a positive reaction with nitroprusside.

Which of the following may be associated with morphologic examination of spermatozoa?

Papanicolaou stain may be used. The morphologic characteristics of spermatozoa are best evaluated by means of smears stained with Papanicolaou stain. Other stains used include Kernechtrot, Giemsa, basic fuchsin, crystal violet, and hematoxylin. When oil immersion is used, a minimum of 200 spermatozoa should be evaluated for morphologic characteristics. Although sources differ as to the exact number, it is generally established that at least 60% of the sperm should have normal morphologic features. When this microscopic analysis is performed, the presence of erythrocytes, leukocytes, epithelial cells, and microorganisms should be indicated.

To detect more easily the presence of casts in urine sediments, which microscopic method can be used?

Phase-contrast microscopy To better diagnose renal and urinary tract diseases, it is necessary to examine urinary sediment carefully by the most appropriate microscopic method available. Formed elements in the urine, such as cells and casts, are more easily differentiated by the use of phase-contrast microscopy. This is especially true for the identification of the more translucent elements such as hyaline casts. Phase microscopy tends to enhance the outline of the formed elements, allowing them to stand out and be more easily distinguished.

With the development of fetal lung maturity, which of the following phospholipid concentrations in amniotic fluid significantly and consistently increases?

Phosphatidyl choline The alveolar concentrations of the various phospholipids (surfactants) change during fetal lung development, and because these changes are reflected directly in the amniotic fluid, a number of investigations have shown that analysis of the fluid can provide good predictive information for the development of respiratory distress syndrome in the newborn. The concentrations of sphingomyelin and phosphatidyl inositol increase until about 32-34 weeks of gestation and then decline. Conversely, lecithin (phosphatidyl choline) and phosphatidyl glycerol concentrations increase rapidly after 32-34 weeks of gestation, and their concentrations relative to those of the other phospholipids are useful in assessing the development of fetal lung maturity.

Which term is defined as a urine volume in excess of 2000 mL excreted over a 24-hour period?

Polyuria On the average, a normal adult excretes 1200-1500 mL of urine daily. "Polyuria" is a term used to describe the excretion of a urine volume in excess of 2000 mL/day. In oliguria, the daily urine excretion is less than 500 mL, and in anuria the urine formation is completely suppressed. Hypersthenuria refers to urines of any volume containing increased levels of dissolved solute.

How should controls be run to ensure the precision and accuracy of the reagent test strips used for the chemical analysis of urine?

Positive and negative controls should be run on a daily basis. It is necessary that any deterioration of the strips be detected in order to avoid false-positive or false-negative results. The use of positive and negative controls will act as a check on the reagents, on the technique employed, and on the interpretive ability of the person or instrument performing the test.

Xanthochromia of cerebrospinal fluid (CSF) samples may be due to increased levels of which of the following?

Protein A variety of substances in CSF specimens have been associated with a xanthochromic appearance. Among those substances are oxyhemoglobin, carotenoids, bilirubin, and protein. The appearance of the specimen by itself is not usually specific for a particular disease state, but it may provide useful information in comparison with other findings. Glucose, magnesium, and chloride do not contribute to the color of the specimen.

Which of the following systems utilizes polyelectrolytes to determine the specific gravity of urine?

Reagent strip A clinically useful test for assessing the concentrating and diluting ability of the kidneys is the determination of urine specific gravity. The specific gravity is a measure of the proportion of dissolved solids in a given volume of solvent. Polyelectrolytes are incorporated into urinalysis reagent strips. A dye also present in the strips will change color because of a pKa change in the polyelectrolytes of the urine. The color obtained is compared with a set of standard colors, each color correlating with a different specific gravity concentration. The TS meter is a specific type of refractometer that utilizes the close correlation of a solution's refractive index with its solute concentration to determine the specific gravity of urine. The refractive index is the ratio of the velocity of light in air to the velocity of light in a solution, this being comparable to the number of dissolved particles in that solution. An osmometer measures the concentration of dissolved solute in the sample, usually through its relationship to freezing point depression.

A 35-year-old man has just experienced severe crush injuries sustained in a car accident. He has a broken pelvis and right femur and has numerous abrasions and contusions. A random urinalysis specimen shows a brown color and clear appearance. pH is 6.0, protein is 1 + , and blood is 3+. There is, however, only 0-1 RBC/hpf, along with 0-3 WBC/hpf. Casts found include hyaline (0-2/lpf) and granular (0-1/Ipf). Other urine results are normal. Which of the following is true about this patient?

Rhabdomyolysis may be a cause for the discrepant chemical/microscopic blood findings. In addition to hemoglobin, the muscle protein myoglobin can cause a positive blood result in chemical reagent strip testing. Both hemoglobin and myoglobin possess pseudoperoxidase activity detected by the "blood" chemistry test. Muscle-crushing injuries (rhabdomyolysis) will release myoglobin from the muscle. The myoglobin, being a small molecule, is readily excreted by the kidneys. Myoglobinuria can lead to acute renal failure. Myoglobin can be distinguished from hemoglobin in urine by an ammonium sulfate screening test. Myoglobin will remain soluble in 80% ammonium sulfate and give a positive filtrate blood reaction after the precipitation of hemoglobin. The patient's pathology involves neither red blood cells nor bilirubin. The severe stress may be responsible for both the urine protein and granular cast results.

Each of the following is included in the quality assurance program for a urinalysis laboratory. Which one represents a preanalytical component of testing?

Setting collection guidelines for 24-hour urines Prenalytical components of laboratory testing include all variable that can affect the integrity or acceptability of the patient specimen prior to analysis, such as correct collection technique. Analytical factors affect the actual analysis of the specimen (temperature, condition of equipment, timing, presence of interfering substances). Postanalytical factors affect the final handling of the results generated (reporting units, critical values, acceptability of quality control).

A patient has been diagnosed with an upper gastrointestinal bleed. Which of the following would be characteristic for this condition?

Stool with a much darker brown/black color The hemoglobin released from RBCs in an upper gastrointestinal bleed will have time to become denatures and oxidized as it travels the entire intestinal tract. This will make the stool become much darker in color by the time the hemoglobin is excreted. Clay-colored stools will result from an obstruction of the biliary duct, preventing bilirubin from entering the intestines to be converted into urobilinogen and then into urobilin. Stools with red streaks are more likely to result from a lower gastrointestinal bleed, as from the colon. Increased mucus will be associated with intestinal inflammation.

The estimation of hyaluronic acid concentration by measurement of viscosity is useful in evaluating which type of fluid

Synovial Synovial fluid is a form of plasma ultrafiltrate with added hyaluronic acid. Decreased viscosity and poor mucin clot formation are indications of the decreased hyaluronate concentration of synovial fluid. Either of these findings is usually an indication of inflammation. Because the viscosity of synovial fluid is normally very high, it can be estimated by the length of string formed when the fluid drops from a syringe. The term "mucin" in the mucin clot is a misnomer, because mucin is not present in synovial fluid.

Compared to the fecal occult blood test, which of the following is a disadvantage of performing a DNA-based test to detect colon cancer?

The DNA test is more expensive. DNA-based tests for detecting mutations within colon cells are generally more expensive than the fecal occult blood (FOB) methods using the pseudoperoxidase propery of hemoglobin. Advantages, however, include no diet or medication restrictions prior to the testing, use of a single stool sample, and a sensitivity (50-73%) that far exceeds that of the FOB test (13-35%) for detecting colon cancer. It is, however, less sensitive than colonoscopy, which can detect 95% of colon cancers. Gene mutations associated with colorectal cancer include APC (adenomatous polyposis coli)

A routine urinalysis is performed on a young child suffering from diarrhea. The reagent test strip is negative for glucose but positive for ketones. These results may be explained by which of the following statements?

The child is suffering from increased catabolism of fat because of decreased intestinal absorption. Although a positive result on a urine test for ketones is most commonly associated with increased urinary glucose levels, as in diabetes mellitus, other conditions may cause the urine ketone test to show positive results while the urine glucose test shows negative results. In young children, a negative glucose reaction accompanied by a positive ketone reaction is sometimes seen. Ketones in the urine may be seen when a child is suffering from an acute febrile disease or toxic condition that is accompanied by vomiting or diarrhea. In these cases, because of either decreased food intake or decreased intestinal absorption, fat catabolism is increased to such an extent that the intermediary products, known as ketone bodies, are formed and excreted in the urine.

A 47-year-old female patient with controlled type 2 diabetes mellitus complains of urinary frequency and burning. She provides a first-morning, clean-catch specimen. Results show color = yellow;appearance = cloudy; pH = 6.5; a representative microscopic high-power field is shown in Color Plate 46 Which of the following is true for this patient?

The major formed elements are white blood cells and yeast. There are minimal bacteria present in color plate 46. Both budding yeast and WBCs predominate this microscopic field. Patients with diabetes mellitus are prone to such yeast infections because of the increased glucose in their urine. The epithelial cells visualized in this field are transitional and not squamous. They can be distinguished by their size (about 15-20 μm), less cytoplasm than a squamous cell would have, and their central nucleus. Increased squamous epithelial cells would suggest improper collection, whereas transitional cells, if greater than 5 cells/hpf, would indicated pathology. There are fewer than 5 RBCs in this field, and that would be below the sensitivity of the blood pad on the reagent strip.

A 67-year-old male has routine testing done and shows an estimated glomerular filtration rate (eGFR) of 42 mL/min/1.73 m2. Which of the following is true for this patient?

The patient is in Stage 3 chronic kidney damage. The eGFR calculation is based on the "modification of diet and renal disease" formula recommended by the American Kidney Foundation. It does not use a urine sample at all, but instead requires only a serum creatinine and the patient's age, gender, and race. Values less than 60 mL/min/1.73 m^2 are considered abnormal and need to be followed up. This patient's value places him in stage 3 kidney damage (35-59 mL/min/1.73 m^2). This calculation is considered more accurate than the Cockgroft-Gault formula, but there are limitations based on the standarization of the creatinine method used.

Which of the following is the major organic substance found in urine?

Urea Although sodium is the major inorganic molecule found in urine, urea is the major organic molecule excreted. Urea is a waste product of protein/amino acid metabolism. Its level in a normal 24-hour urine with a glomerular filtration rate of 125 mL/min would be 400 mmol/day. Glucose excretion will average less than 1 mmol/day. The excretion of the inorganic molecules sodium and potassium would be 130 and 70 mmol/day, respectively.

Urine specimens should be analyzed as soon as possible after collection. If urine specimens are allowed to stand at room temperature for an excessive amount of time, the urine pH will become alkaline because of bacterial decomposition of

Urea At room temperature, the amount of bacteria present in a urine sample will increase. The bacteria are capable of metabolizing the urinary urea to ammonia. The ammonia formed through this process will cause an alkalinization of the urine.

Which urinalysis reagent strip test will never be reported out as "negative"?

Urobilinogen The sensitivity of a method is the lowest concentration of the analyte that will result in a detectable reaction signal. The protein, bilirubin, and nitrite readout color scales each have a color associated with analyte concentrations less than the method's sensitivity, called "negative." Urobilinogen's readout color scale begins with its lowest reportable value, but there is no pad associated with concentrations less than this.

The physical characteristic of color is assessed when a routine urinalysis is performed. What substance is normally found in urine that is principally responsible for its yellow coloration?

Urochrome, a yellow-brown pigment derived from urobilin, is principally responsible for the yellow coloration of normal urine. Urochrome is excreted at a constant rate, showing no diurnal variation. Therefore, the color of normal urine, which may range from straw to deep amber, is dependent on the concentrating ability of the kidney and the volume of urine excreted.

Which of the following is true about the final concentrating of urine in the kidney?

Vasopressin controls the collecting duct reabsorption of water. The distal convoluted tubule and collecting duct provide water reabsorption through the action of antidiuretic hormone (vasopressin). The renin-angiotensin- aldosterone system is responsible for sodium reabsorption by the distal and collecting tubules. Decreased plasma volume leads to pressure alterations detected by receptors located in the kidney's juxtaglomerular apparatus and the right atrium of the heart. These changes trigger the production of renin and antidiuretic hormone, respectively.

A characteristic of substances normally found dissolved in the urine is that they are all

Water soluble To be found in urine, a solute must be water soluble. Solutes can be inorganic (e.g., sodium) or organic (e.g., urea). Excreted waste products, meaning end products of metabolism, are creatinine, urea, and uric acid. Some excreted solutes, however, are not present as waste but as overload, such as glucose or sodium.

The final phase of degeneration that granular casts undergo is represented by which of the following casts?

Waxy Waxy casts represent the final phase of granular cast degeneration. As the fine granules of the granular casts lyse, highly refractive, smooth, blunt-ended waxy casts are formed. When waxy casts are found in the urine sediment, the implication is that there is nephron obstruction caused by tubular inflammation and degeneration.

Which of the following statements applies to the proper collection and handling of CSF?

With low-volume specimens, a culture is performed first, before cell counts are done. CSF must be collected in sterile tubes. The first tube is generally used for chemistry and serology studies, the second tube is employed for bacteriologic examination, and the third tube is used for cell counts. Tubes used for chemistry and bacteriologic studies should be centrifuged before use. CSF should remain uncentrifuged for cell counts. Low-volume specimens need to be cultured first (to ensure sterility) before any other test is performed. Because the analysis of CSF should be performed immediately, it is critical that personnel on all shifts be able to perform the necessary testing.

A patient sends the following question to an online consumer health Web site: "I am a 22-year-old female who experienced increasing headaches, thirst, and decreasing energy. I was studying in the library when I felt lightheaded and passed out. I was taken to a hospital emergency department and they told me that my serum Acetest® was 40 mg/dL and urine glucose was 500 mg/dL. What does this mean?" How would you reply?

Your lab results pattern suggests diabetes mellitus. A positive urine glucose plus a positive serum ketone strongly suggest uncontrolled diabetes mellitus. There is an increased rate of fatty acid oxidation occurring in light of the inaccessibility of the glucose, especially to skeletal muscle. If the patient had only been dieting, the glucose would be negative.

The colorimetric reagent strip test for protein is able to detect as little as 5-20 mg of protein per deciliter. What may cause a false-positive urine protein reading?

pH is greater than 8.0. The principle of the reagent strip method for the detection of protein injuring is based on a color change in an indicator system, such as tetrabromophenol blue, that is buffered to pH 3. The buffering capacity of the strip is sufficient provided that the urine pH does not exceed 8.0. Within the normal urine pH range of 4.5-8.0, a change in color in the reagent strip is an indication of the presence of protein in the urine. With a urine pH greater than 8, the buffering capacity of the strip may be exceeded, and a false-positive color change in the impregnated area will reflect the pH of the urine rather than the presence of protein. The presence of vitamin C, uric acid, or glucose in urine will not affect the test for protein.