urinalysis specimen, collection, chemical
: Would it be possible for a patient's refractometer reading to be greater than 1.035?
Yes this is absolutely possible. Patient's that have excess or large amount of solute particles in their urine "may" have an S.G. that is > 1.035. For example, a patient that is excreting X-ray dye media may have a S.G. as high as 1.040 or 1.050. In most facilities if the urine dipstick specific gravity reads 1.030 then a refractometer S.G. will be performed. Note: Usually 1.030 is the highest value that can be obtained on a urine dipstick S.G. Therefore, how would you know if the urine "actually" has an S.G. of 1.030 or higher??? If a manual S.G. by refractometer is performed and the reading is above the 1.035 mark on the scale then the urine sample must be diluted and rerun to gain an accurate result.
Is it normal to have urobilinogen in the urine?
Yes, absolutely. In fact it is "expected" that some urobilinogen will be present in the urine. A "negative" urine urobilinogen actually points towards a very serious condition called biliary obstruction.
Is it possible to have a positive blood urine dipstick without seeing red blood cells on the microscopic exam?
Yes, it is possible because the positive result may be due to hemoglobin released from lysed red blood cells. This is known as "hemoglobinuria".
Can a patient have a UTI without the nitrite portion of the dipstick being positive?
Yes, remember not ALL bacteria have the ability to reduce nitrate to nitrite. Also, it can take up to four hours for bacteria to reduce nitrate to nitrite. Therefore, if the bacteria has not been present in the bladder for greater than 4 hours, the test will be negative even if the bacteria has the ability to reduce nitrates.
refractive index
a measure of the light-bending ability of a medium
Tubular proteinuria
a proteinuria is observed due to an impaired function of the tubules to reabsorb proteins Box 6-3 on page 94 in Brunzel Since the proteins that are expected to be reabsorbed are of the smaller molecular weight, the extend of the proteinuria is generally not as severe as seen in glomerular proteinuria. The total urine protein concentration is typically "less than" 2.5 g/dL and contains mostly the globulin types of proteins. ("Although albumin is found in increased amounts, it does not approach the level found in glomerular proteinuria
urine odor after sitting too long
a urine specimen sits at room temperature for longer than 2 hours, it can produce an ammoniacal scent because of bacteria present converting urea (a normal urine component) to ammonia § . If a "fresh" urine has an ammoniacal scent, that is a good clue that bacteria are present and the person is suffering from a urinary tract infection.
bilirubin and urobiliogen test
ascobic acid will cause false negative results and yes, there is a tablet test for bilirubin called the ictotest that will be discussed in the Confirmatory Test document.0
Renal proteinuria
caused by a glomerular or tubular problem in the nephron. If the glomerulus is damaged, increased amounts of plasma protein are allowed through the filtration and are seen in the ultrafiltrate.
post renal protein
caused by inflamamtion, malignancy, injurty/ trauma and contaimination see pus, vaginal secretions, prostatic secretions, and menstrual or hemorrhoidal blood
clarity
clear- no or rare particles. hazy or slightly cloudy-can read newspaper, some particles seen cloudy- difficult to read newspaper, significant particles . contaminants, crystals, epithelial cells, fat, microbes turbid- cant read newspaper through. semen, contaminants, prostate fluid,
characteristics of urine
color clarity odor concentration volume
abnormal urine colors
dark yellow amber orange red pink brown blue/green
postural orthostatic proteinuria
defined as normal urinary protein excretion during the night but increased excretion during the day, associated with activity and upright posture
specific gravity
expression of concentration" of dissolved solute particles. The typical range of measurement for SG on the dipstick is from 1.000 to 1.030. Remember, it is "physiologically impossible" for a patient to have a S.G. of 1.000. (1.000 is the SG of distilled water). An increased specific gravity can be found in urine samples with increased concentrations of substances such as glucose, protein or urea. Decreased specific gravities are found in more dilute urine and a particular disease that commonly has a low S.G. is Diabetes insipidus A consistent urine S.G. of 1.010 is significant since this is the specific gravity of the "ultrafiltrate" which is protein free!
renal proteinuria
glomerular proteinuria
nephrotic syndrom
group of clinical signs and symptoms caused by excessive protein loss in urine persistance of glomerylar proteinuria is characterized by: excessive proteinuria- amounts greater than 3.5 g / dL hypoalbuminemia - decreased amount of albumin (the major contributor to the body's total protein) in the blood hyperlipidemia - increased amounts of lipids (fats) in the blood lipiduria - lipids in the urine (a very classic indication of Nephrotic Syndrome is the presence of "oval fat bodies" in the urine)
leukocyte esterase
indicates the presence of white blood cells in the urine, which can point to a UTI The leukocyte esterase portion of the dipstick will become positive in the presence of increased numbers of granulocytes, which is indicative of inflammation. Normally, 0-8 white blood cells may be seen on the urine microscopic without alarm. However, 20 or more WBC seen microscopically would be considered pathologic. Fortunately, the L.E. portion of the dipstick is sensitive to the detection of as few as 10 or more WBC. The most common cause of "leukocyturia is a bacterial infection involving the kidneys or urinary tract, such as pyelonephritis, cystitis, or urethritis."1
refractive index of light theory
indirect way to measure specific gravity the ratio of light refraction
contaminants in urine
lotion, powder, feces, talc
random collection
method is used to collect urine that requires no special preparation § The patient is simply instructed to void in a clean, dry, sterile container. routine testing § Although this is the most common type of sample collected, it may not be an accurate reflection of the patient's condition if the patient has had an excessive fluid intake or exercise, both of which will affect urine composition
Overflow proteinuria causes
most commonly associated with increased production of abnormal low molecular weight proteins (eg, light chains in multiple myeloma, myoglobin in rhabdomyolysis) that exceeds the reabsorption capacity of the proximal tubule, leading to spilling of the protein into the urine
color
normal: a pale/light yellow or straw color due to the pigment urochrome that is excreted at a constant rate due to normal metabolism pale/colorless if the urine is dilute (urochrome pigment is diluted) dark urine is concentrated (more urochrome pigment)
speciment handling
o Any urine specimen should be transported to the lab and tested within 1-2 hours. o If a sample cannot be analyzed within 1-2 hours, the best way to preserve the integrity of the specimen is by refrigeration. o There are many other types of urine preservatives to use - see Table 2-4, page 24 in Brunzel for a list of these preservatives and their uses. o If a urine sample is not properly preserved, there are a number of changes that can occur in the urine, which will lead to false or inaccurate results. The most common error in urine testing is failure to use a FRESH specimen! It is very important that you learn what these changes are - see Table 2-3, page 23 in Brunzel.
reagent strips
o Urine reagent strips, like the drawing in figure 6-1 on page 86 in Brunzel, are affectionately known as "dipsticks". Know that reagent strips, chem sticks or multistix are all speaking of the same apparatus - the "dipstick". Although the other terms are certainly more proper they are not used as commonly.
chemical analyis background
o like urea, water and phosphates o Urine is formed by the kidney in an effort to "excrete" or "get rid of" waste products § Components such as urea, phosphates etc are substances that "should" be removed from the body daily o , the components we are testing for in the Chemical Analysis part of the complete urinalysis does NOT test for what is expected to be excreted in the urine. Rather, the chemical analysis is used to identify the components that should NOT normally be excreted in the urine, such as: Glucose, Protein, Bilirubin etc.
urinalysis
o non-invasive fluid biopsy of the kidney. o By performing a physical, chemical & microscopic analysis on a urine sample, much information about kidney function can be obtained. o As stated in your textbook, since "urine is an ultrafiltrate of plasma, it can be used to evaluate and monitor body homeostasis and many metabolic disease processes.
urinalysis background
o routine urinalysis test includes the physical, chemical, and microscopic examination of a urine sample o The physical examination includes reporting the physical characteristics or properties of a urine sample o you must have 10-12mL of a well-mixed sample and view it through a clear container against a white background with good lighting. (See Table 5-1, page 70 in Brunzel.)
solutes measured on strip
only ionic particles like na+, cl-k+ and nh4+
prerenal proteinuria
overflow proteinuria -increase in plasma low molecular weight proteins leads to increased excretion in urine muscle injury, intravascular hemolysis, infection, inflammation, multiple myeloma myoglobin, hemoglobin, acute phase reactants, abnormal proteins such as Ig light chains
reagent strip colors
pages 86 - 87 changes based on chemical change monitored
high molecular weight and renal function
presnese of high molecular weight does not reflect renal concentrating ability solutes only present because of abnormal processses but not concentration ability
when specimen is used
random -Routine screening, cytology studies with prior hydration, fluid deprivation tests first morning routine screening, good recovery of cells and cast, confirm postural or orthostatic proteinuria, cytology studies timed quantitative chemical analysis, clearance test, cytology studies, evaluation of fitula
specimen type
randon first morning timed collection
collection techniques
routine void midstream clean catch catheterized specimen suprapubic aspiration collection bag
sweet or fruity urine
scent is associated with diabetes mellitus due to the presence of ketones (a breakdown product of lipids)
chemical tests
specific gravity pH blood leukocyte esterase nitrite protein glucose ketones bilirubin and urobilinogen
cause of glomerular protein
strenuous exercise diabetes drugs fever dehydration hypertension extreme cold exposure glomerular diseases
osmolality
the concentration of solutes in body fluids osmoles or particles per kilogram of water molecular weight will not influence monitor concentraiton ability of the kidneys,monitor renal disease, monitor fluid and electrolyte balance, and diagnose cause of polyuria
ultrafiltrate
the fluid resulting from the initial filtration of metabolic by-products from the filtered blood within the tubule of the kidney
Glomerular proteinuria
the most common cause of increased protein found in the urine and is considered the most clinically serious. Large amounts, > 2.5 grams/dL, of protein will be released into the urine - see Box 6-2 on page 92 in Brunzel for a list of causes of Glomerular proteinuria
What is the "alkaline tide"?
this is the concept that an individual's urine will become slightly more alkaline after or during a meal since the stomach is secreting acids to aid in digestion.
acid urine
this type of urine creates uric acid or cystine stones high protein diet sleep metabolic acidosis (ketoacidosis, starvation, severe diahhrrea, uremia, poisons respiratory acidosis such as emphysema or chronic lung disease urinary system disorders such as UTI with acid producig e coli medications used to induce ammonium chloride, ascorbic acid, methionine, mandelic acid Table 6-3 on page 90 in Brunzel
specific gravity methodology
urinometer chemical dipstick refractometer
alkaline urine
vegetarian diet metabolic alkalosis such as vomiting respiratory alkolosis such as hyperventalation urinary disorder such as UTI with urease producing bacteria like proteus and pseudomonas. renal tubular acidosis medications used to induce sodium bicarbonate, potassium citrate and acetazolamide
variations in urine color
§ Any variation in a normal urine color can be due to a disease state or disorder or due to an ingested material (medication or food). § Urine color is always reported as a part of the routine urinalysis test.
timed collection
§ In a timed collection urine is collected over a set period of time, 12 or 24 hours. § Urine concentration of an analyte may vary due to circadian or diurnal variation, state of hydration, effect of exercise, body metabolism, or excretion rates. § This sample is used to quantitatively measure an analyte (such as creatinine or protein). § Collection of a 24-hour urine typically begins in the morning. The patient is instructed to void and discard the first morning sample on Day 1 of collection, then collect all urine voided for the next 24 hours including Day 2 first morning sample. When the sample is received in the lab, it should be mixed thoroughly, the total volume recorded, and then aliquoted (divided) if more than one test is required. (see Box 2-1, page 20 in Brunzel)
specific gravity
§ Specific gravity is a way to state the density (the mass of solutes present in a certain volume of solution) of the urine. The formula to calculate specific gravity shows that it is a ratio of the density of urine compared to the density of an equal volume of water: § S.G. = Density of urine divided by the Density of an equal volume of water § Normal specific gravity for a random urine sample is 1.003-1.030 and for a 24-hour urine is 1.016-1.022. The density of water is always 1.000.
What is the range for normal specific gravity of a 24 hour urine sample smaller than the range for a random urine sample?
§ The 24 hour urine specific gravity range is narrower because it is the "average" of all the urine collected throughout the day. A random urine sample takes into consideration the variation in a patient's "state of hydration" throughout the day and therefore has a broader normal specific gravity range.
refrigerated urine
§ There is one "nonpathologic" cause for a cloudy or turbid urine that deserves mentioning. When a sample is refrigerated, sometimes chemical components of the urine can "precipitate out" and form amorphous (lacking shape) crystals. When amorphous phosphates form in alkaline urine a white precipitate is observed and when amorphous urates are formed in an acid urine a pink precipitate is seen.
first morning
§ known as a first voided sample; § the patient is instructed to void before going to bed and then the first morning sample is collected. § This type of sample is ideal for testing substances that need concentration (pregnancy test or orthostatic proteinuria) or incubation for detection (bacteriuria) because the urine has been retained in the bladder for at least 8 hours. § The sample can also be used for routine urinalysis testing.
Tamm-Horsfall protein
Hyaline casts (non-specific)
S.G. Clinical Significance
Hypersthenuria is a specific gravity (SG) >1.010, meaning the urine is very concentrated. Hyposthenuria is a SG of <1.010, and the urine is very dilute. Isosthenuria is when multiple urine samples have a fixed SG of 1.010. This occurs when the kidney cannot reabsorb or secrete substances properly, so the SG of the urine is the same as that of plasma. It is possible for urine to have a specific gravity of 1.010 and not be isothenuric. If isothenuria is present, the specific gravity of the urine will ALWAYS be 1.010.
Postrenal proteinuria
Increased protein in the urine caused by infections/inflammation that add protein to the urine after its formation. Post-renal proteinuria occurs with inflammation of the urinary tract. Common conditions thought to be associated with post-renal proteinuria are urinary tract infection, nephrolithiasis, and tumors of the urinary tract. Post-renal proteinuria usually resolves when the underlying condition has resolved.Mar 25, 2020
urinometer
Many years ago, a urinometer was used to measure specific gravity. Urine was poured into a specialized cylinder and a mercury weight flotation device with a specific gravity scale was "floated" in the cylinder (see figure 5-3, page 75 in Brunzel). This method was dependent on the "buoyancy" of the sample. In general, the more particles that were present in the urine, the higher the mercury weight device would float and therefore the higher the specific gravity. In addition to number of particles, the urinometer was also dependent on size and weight of dissolved particles. A urinometer is no longer used because it required such a large volume of urine and a device that includes mercury.
other carbohydrates in urine
It is important to note that "other carbohydrates" may appear in the urine (although the dipstick will not become positive because of the its glucose specificity). Some congenital enzyme deficiencies will result in carbohydrates, such as lactose or galactose, appearing in the urine. A tablet test used to identify a broad range of reducing substances, known as the Clinitest, is performed. (we will discuss the Clinitest in greater detail in the Confirmatory Test document)
midstream clean catch
Most common procedure for collecting any type of urine specimen bacterial culture of the urine is ordered. It can also be used for routine urinalysis. The patient is instructed to properly cleanse his/her external genitalia with a mild antiseptic solution (no oxidizing agents, as these can cause interference with chemical analysis of the urine). After cleansing, the patient must void & discard the initial urine stream, then collect the midstream portion in a clean, dry and sterile container. The patient then voids and discards the end of the stream. This type of collection technique is required to avoid bacterial contamination that could be present on the genitalia.
What should you do if you receive a S.G. of 1.030 on the urine dipstick?
Most facilities will want to verify the S.G. by the refractometer method in the event that the "actual" S.G. is greater than 1.030. Check with your laboratory's protocol.
other urine scents
Mousy when phenylketonuria is present Maple syrup with Maple Syrup Urine Disease Rancid in conditions such as Tyrosinemia Table 5-4 on page 74 in Brunzel)
Is it normal to have bilirubin in the urine?
No, bilirubin in the urine will indicate some type of liver dysfunction.
Should glucose normally be found in the urine?
No, glucose that is found in the ultrafiltrate is typically completely reabsorbed.
foam
Normally a urine sample will foam if mixed sufficiently and will go away upon standing. One instance where an increased amount of foam may be seen is when there is an increased amount of protein in the urine sample. Although foam is NEVER reported as a part of the routine urinalysis, it may be a clue as the urinalysis test is performed.
protein
Normally there is approximately 150 mg of smaller proteins (1/3 albumin & 2/3 globulins) found in urine which comes from the ultrafiltrate. However, some proteins actually originate in the tubules of the nephron. These proteins are known as Tamm-Horsfall proteins and are the basic matrix of urinary "casts" (we will discuss casts in much greater detail in the microscopic exam document). Proteinuria, "the presence of increased amounts of protein in the urine", is "often the first indicator of renal disease
catheterized specimen
Catheterization is a procedure performed by a physician or nurse where a sterile tube is inserted into the bladder. Urine is collected in this way if the patient has trouble voiding or if a suitable specimen cannot be obtained. The urine specimen may be used for routine screening, bacterial culture or cytological exam (observe for cancer cells).
Bilirubin & Urobilinogen
Once hemoglobin is liberated from the red cell it is broken down (through many steps that we will not cover in this document) to bilirubin in the RES (reticuloendothelial system). This bilirubin attaches to albumin and is called "Indirect or Unconjugated" bilirubin. Unconjugated bilirubin is transported to the liver where it is converted to "Direct or Conjugated" bilirubin. Conjugated bilirubin is then delivered to the small intestine where bacteria converts it to Urobilinogen. Urobilinogen is an excretable form of bilirubin and is released in both the feces and the urine.
pH
One of the important roles of the kidney is to regulate acid-base balance. The normal urine pH ranges from 4.5-8.0 with an average pH equaling 5.0-6.0. Note: pH values above or below the range of 4.5-8.0 are physiologically impossible
clarity causes
Pathologic: Red blood cells, white blood cells, microbes, renal epithelial cells, fats and lipids, abnormal crystals , seamen or prostatic fluid, feces, cuts non pathologic normal solute crystals like urate, phosphate, calcium oxalate. Squamous epithelial cells, mucus, semen and prostatic fluid, contaminants
reagent strips setup
Reagent strips or dipsticks come from the manufacturer and are thin pieces of narrow plastic with several reagent "pads" specifically arranged on them. Each pad has all of the necessary chemicals needed for a reaction EXCEPT for the particular solute or analyte that is being testing. For example, the glucose pad has all the chemicals and substances "impregnated" (soaked into) to perform the glucose oxidase reaction. If a urine sample has glucose in it, this glucose will react with all of the chemicals on the glucose portion of the dipstick and cause a color change. The color that is produced is compared to a color chart that is typically affixed to the side of the dipstick reagent bottle. When reading the color and comparing it to the chart, it is ESSENTIAL that you allow the reaction to occur for the specific amount of time that is stated on the chart and read the color as accurately as possible. Identifying different shades of a particular color is so important that typically color blindness tests are administered to all laboratory personnel. Thankfully, these days there are automated instruments to accurately identify the color changes but it is not unusual for health care facilities to still use the good ole manual dipstick method. We will be performing the dipstick method in our student laboratory.
Routine Void
Requires no patient prep Collected by having patient void into appropriate container Patient normally needs no assistance other than clear directions Can be random or first morning specimen
dipstick testing technique
Review and learn the "specifics" of the proper technique to test a urine sample using a reagent strip. Learn the information found in Box 6-1 on page 88 in Brunzel. Did I mention you need to "learn" this information and not "memorize" it?? We will be using this technique in our laboratory sessions and you are expected to come prepared.
increased urobilinogenand bilirubin
See Table 6-22 on page 112 in Brunzel for a list of causes of increased bilirubin and urobilinogen in the urine prehapatic: hemolytic disease, ineffective erythropoeisis hepatic: hepatitis, cirrhosis, genetic post hepatic: gallstones, tumors, fibrosis
Sensitivity vs. Specificity
Sensitivity - proportion of people with condition that tested positive (SnNout - if neg can rule it out) Specificity - proportion of people without the condition who tested negative (SpPin - if positive, rule it in)
urine clarity
Should be clear or transparent Variations are typically reported as hazy, cloudy, or turbid. Review Table 5-3, page 72 in Brunzel for variations in urine clarity and their causes.
What is a "distinguishing feature between hematuria and hemoglobinuria"?
The appearance or clarity of the urine sample is a distinguishing feature. Hematuria will cause the sample to be cloudy or turbid due to the intact red blood cells where hemoglobinuria will have a clear appearance (and generally a reddish color). . Even though hematuria can be caused by bleeding anywhere along the urinary system, if red cells are accompanied by red cell casts, this condition is indicative of glomerular or tubular injury. Table 6.9 on page 96 in Brunzel
: In the body, where does the majority of bilirubin come from?
The breakdown of hemoglobin which is released from the red blood cells.
density and temperature
The density of a substance generally decreases as its temperature increases.
glucose reagent strip
The glucose portion of the urine dipstick is "specific" for the detection of glucose and not other carbohydrate sources. Urine glucose concentration of < 20 mg/dL are still considered normal. However, because of the dipstick's sensitivity this small amount of glucose will NOT be detected. The dipstick's sensitivity will decrease if the test is run on a sample that is still at refrigerator temperature or if the sample has an elevated specific gravity. The most common method of analysis of glucose on a dipstick is the "glucose oxidase" reaction (see page 106). Again, false negative results for glucose may be obtained in the presence of large amounts of ascorbic acid.
glucose
The kidney has a renal threshold for glucose equaling 160 - 180 mg/dL. This means if a patient's blood glucose level rises above 160-180 mg/dL, glucosuria (glucose in the urine) will result. In other words, the renal threshold represents the maximum amount of analyte or substance the tubules are able to reabsorb. Any glucose amount exceeding this value will "spill over" into the urine. Like protein, glucosuria may be caused by "prerenal" (conditions existing before the kidneys) or renal conditions. See Table 6-17 on page 104 in Brunzel for a listing of causes of glucosuria. diabetes hormonal disorders, liver disease, pancreatic disease
The protein portion of the urine dipstick is specific for Albumin. Therefore, what would the urine dipstick result be in a condition of Tubular proteinuria?
The protein urine dipstick result would most likely be negative or only slightly positive. Tubular proteinuria is typically due to increased amount of globulin proteins and smaller amounts of albumin.
ketone strip
The reagent strip chemical reaction is based upon the "nitroprusside" reaction and is specific for acetoacetate and acetone (this means that the B-hydroxbutyrate type of ketone is NOT detected).
What color will the urine be if increased amounts of bilirubin are present?
The urine will typically be a dark yellow, amber or brown color. This urine color is important because it indicates an increased amount of bilirubin and it also causes interference and false positive results on the other dipstick pads.
How can globulins be detected in the urine if they do not cause the urine protein dipstick to become positive?
There is a protein "precipitation" test method called an SSA (sulfosalicyclic acid) which will detect both the globulin and albumin types of protein. (we will learn more about this test in the Confirmatory Test document)
Quality Control of dipstick
To ensure that the dipstick pad reactions are functioning properly a "normal" (negative) and "abnormal" (positive) control should be run on the reagent strip bottle each day. These controls are typically purchased from a manufacturer and should also be handled, processed and stored properly. Running QC on the reagent strips not only tests the accuracy of the dipstick but it also evaluates the technicians technique.
chemical dipstick
Today the most common way to assess specific gravity is with the chemical dipstick (we will learn about that in our next unit on chemical analysis)
What would the final refractometer S.G. be if a reading of 1.019 was obtained from a 1/2 urine dilution?
Two things first. Notice that S.G. results do not have "units" such as grams or liters etc. and in the case of a urine dilution you must take ONLY the last 2 numbers in the S.G. reading and multiply by the dilution factor to get the final specific gravity result. In this example the final S.G. is 1.038 (1.019 times the dilution factor of 2 = 1.038)
bacteria and uti
Urinary tract infections can involve the bladder (cystitis), the renal pelvis and tubules (pyelonephritis), or both." The way a UTI develops is either through "the localization of bacteria: "up the urethra into the bladder" - this is known as an "ascending infection" or "from the bloodstream into the kidney and urinary tract" Normally the urine and bladder are sterile. However, in conditions of urinary obstruction, bladder dysfunction, urine stasis (stagnation or non movement) or even catheterization bacteria may be introduced and a urinary tract infection results. Note: The presence of bacteria on a urine microscopic exam may also be due to bacterial contamination in the specimen collection process. Typically, the presence of "both" bacteria and WBC rules out contamination as the cause.
suprapubic aspiration
Urine is collected directly from the bladder by a needle and syringe. A physician performs this procedure only when urine is difficult to obtain. The specimen may be used for routine screening, bacterial culture or cytological exam (observe for cancer cells).
Volume
Urine volume is only reported with a 24-hour or other timed urine specimens. As you learned in a previous unit, urine volume can vary depending on fluid intake and kidney function
Would it be possible for a patient's refractometer reading to be less than 1.000?
Absolutely NOT! Remember that the S.G. of water is 1.000 and if a patient result was <1.000 that would mean there urine has less solute present than water which is not possible.
odor
(Not observed on a routine basis.) Normal urine odor is faint or said to have an "aromatic" odor differences can be caused by a metabolic disroder
concentration
-specific gravity -§ measure the amount of solutes (dissolved particles) present in the urine. § Normally urine is 94% water and 6% dissolved particles, most of which is urea and sodium chloride. § The amount and type of solutes varies based on the diet, exercise and overall health of the patient. § Urine is usually more concentrated in a first morning sample than in a random sample throughout the day (due to the patient's state of hydration). § Solute concentration is a way to assess how well the kidney is able to selectively reabsorb the solute particles. § Abnormal urine concentrations can indicate various renal or metabolic disorders.
dipstick technique
1. Using UN centrifuged urine mix specimen well 2. dip reagent strip briefly into your into wet all reaction pads and start timing device 3. remove excess urine by drawing a district begins remove container or by blotting strip image on absorbent paper 4. at the appropriate time read results of each reaction pad using the color chart on the container discard strip into biohazard
What is the normal adult 24 hour urine volume?
800 to 2,000 milliliters per day (with a normal fluid intake of about 2 liters per day).
false negative nitrite
: False negative results may also be obtained for nitrite with an excess amount of ascorbic acid present.
what cells have leukocyte esterase
: Leukocyte esterase is an enzyme found in the azurophilic granules of granulocytes. Therefore, the presence of lymphocytes in the urine will NOT cause the L.E. portion of the dipstick to become positive.
refractometer
A "manual" specific gravity performed on a refractometer is typically the "back up" method to the dipstick. . The refractometer method is based on the "refractive index of light" theory - see page 76 in Brunzel. As increased numbers of solute particles are present in the urine sample more light is refracted hence giving a higher specific gravity reading. See figure 5-4 on page 76 for a schematic of the refractometer and see figure 5-6 on page 77 for a view of the reading scale within the refractometer.
blood
Although hematuria (red cells in the urine) is a significant condition remember that blood found in the urine can come from "anywhere" along the urinary tract and does not necessarily indicate renal disease or involvement. For example, hematuria may occur if there is bleeding in the bladder, urethra, ureters or kidneys. Additionally, red cells may be present in a urine sample as the result of contamination from a female's menstrual cycle. It is important to note that the blood portion of the dipstick may become positive with the presence of intact red cells or hemoglobin. Other substances with a heme group, such as myoglobin, may also make the blood pad turn positive.
Care and Storage or dipstick
Another important issue to consider is the care and storage of the dipstick. First, always "follow the manufacturer's directions" precisely for the amount of time needed for each reaction to occur. Store the reagent strips away from other chemicals, heat, light and moisture. After removing a dipstick for testing always recap the bottle. Never allow the reagent strip container to remain open and sitting on the countertop. The introduction of moisture can alter the chemicals on the dipstick pads. Never remove the desiccant bag from the reagent bottle and notice that most bottles are either brown or "non transparent" plastic which protects the dipsticks from UV or sunlight.
ketones
Ketones are a breakdown product of lipid metabolism. The 3 types of ketones are: acetoacetate acetone B-hydroxybutyrate
ketonuria
Ketonuria occurs when the blood ketone level exceeds the renal threshold for ketones at 70 mg/dl. See Box 6-5 on page 109 in Brunzel for causes of ketonuria. The most notable causes of ketonuria are perhaps patients with uncontrolled Diabetes mellitus and starvation. There is also a tablet test, acetest, that is performed to somewhat "quantitate" the amount of ketone presence in the urine or serum. (the acetest will be covered in greater detail in the Confirmatory Test document) causes: dibetes mellitus= inability to utilizae available carbs insufficient carb consumption such as starvation, alcoholism, severe cold loss of carbs:vomiting, defective renal reabsorbance, digestive disturbance
nitrite
Some bacteria contain an enzyme, nitrate reductase, that will reduce the presence of nitrate in the urine sample to nitrite. If these bacteria are present, the nitrite portion of the dipstick will become positive however, there is no correlation between a positive result and the "amount" of bacteria present. Nitrite is used only as a screening for bacteria since not all microorganisms have this enzyme. Understandably the presence of bacteria in the urine may indicate a UTI (Urinary Tract Infection). The bacteria typically involved is a gram negative bacilli, like E. Coli, that are part of the "normal flora" of the intestinal tract.
collection bag
Special adhesive bags are available for pediatric urine collection since urine specimens should NOT be obtained from the diaper. The patient's care taker will attach the bag to the external genitalia area and when the sample is voided it is transferred to a sterile collection cup. Occasionally, the collection bag is sent directly to the laboratory. This specimen may be used for routine screening.
What does it mean if the blood portion of the dipstick is negative and red cells are seen on the microscopic exam?
This situation would likely indicate the presence of an interfering substance such as "ascorbic acid" (Vitamin C). Ascorbic acid is a reducing substance that will react with peroxide on the blood pad and remove it from the normal reaction causing a "false negative" result.
