Chemistry BOC
CA 19-9
19-9 has been detected at increased concentrations in the blood of patients with colon cancer and pancreatic cancer. CA 19-9 is also known to be elevated in esophageal cancer and hepatocellular carcinoma
Given the following information, calculate the results in mg/24 hrs for a 24-hour urine protein.Total volume for 24 hours = 2,400 mL Urine protein = 2.7 mg/dL
2.7 mg/dL X 2400 mL/24 hr X 1 dL/100 mL = 2.7 mg X 2400 100 = 64.8 mg/24 hr
All of the following conditions would be associated with an increased level of alpha-fetoprotein, EXCEPT?
AFP is not found in increased levels in patients with prostate cancer. PSA, or prostate-specific antigen, is commonly used to screen for prostate cancer, not AFP.
The accuracy of an immunoassay is its ability to discriminate between results that are true positives and results that are true negatives. Two parameters of test accuracy are specificity and sensitivity. Which of these statements apply to an immunoassay with high specificity, but low sensitivity?
Accurately identifies the absence of disease and has few false-positives
If detected in antibody screen testing, which of the following antibodies is NOT considered clinically significant in prenatal patients?
Anti Lea, Leb, M, and N
Which of the following action describes the MAJOR property of antidiuretic hormone?
Antidiuretic hormone, or ADH, has the important role of conserving body water by reducing the loss of water in urine by changing the water permeability of the distal tubule and collecting duct. An increase in ADH causes concentrated urine since the water is retained and absorbed through the permeable membrane. A decrease in ADH causes the collecting ducts to retain very little water, instead, it is excreted as urine.
Which of the following autoantibodies would be usually found in a patient with Hashimoto's thyroiditis?
Antithyroid peroxidase (TPO)
Carcinoembryonic Antigen (CEA)
As a tumor marker, CEA is associated with colon cancer, in which CEA measurement is mainly used to monitor colorectal carcinoma treatment, to identify recurrences after surgical resection, and for staging to determine the degree of metastasis.2 CEA may also be elevated in malignancies of other tissues, including the stomach, pancreas, breast, lung, and thyroid. Because of this relative low specificity for a tissue or organ system, it is not recommended for use as a screening tool.
CA 125
CA 125 is a mucin tumor marker that is produced primarily by ovarian and endothelial cells.Because CA 125 is sometimes produced by non-cancerous endothelial cells of the uterine endothelium, it is not recommended as a screening test for ovarian cancer in non-symptomatic women.CA 125 is also produced by some non-ovarian carcinomas of the pancreas, lung, breast, and colon.
CA 15-3/CA 549/CA 27.29
CA 15-3 is a mucin tumor marker that is found in certain breast carcinomas.CA 15-3 is produced by healthy tissues of the liver and breast, but to lesser degrees than typically associated with malignancies.
The tumor marker associated with ovarian cancer is:
CA-125
CK-MB
CK-MB is released in the circulation 4-6 hours after symptoms of an AMI and usually peaks within 24 hours. Levels of CK-MB return to normal in about 48-72 hours. This timeframe differs from that of troponin, which stays elevated longer. Trace amounts of CK-MB are also present in skeletal muscle; therefore, skeletal muscle injury can cause CK-MB elevations
A CSF glucose value is 62 mg/dL. What would you estimate the serum glucose?
CSF glucose is roughly estimated to be about 2/3 of the serum glucose level in mg/dL. Therefore: 62 mg/dL = 2/3 x serum glucose serum glucose = 62 mg/dL x 3/2 serum glucose = 93 mg/dL
Thymic hypoplasia is a/an:
Congenital T-cell disorder
What is the glomerular filtration rate for a patient with a serum creatinine of 2 mg/dL, if the urine creatinine was 124 mg/dL and the urine volume was 2.2 L/24 hrs?
Creatinine Clearance = (urine creatinine X urine flow rate) / plasma creatinine; where urine flow rate = volume in mL /24 hours x h/60 min) In this case = creatinine clearance = 124 X (2200/24 x hour/60) / 2 = 94.7 or 95 mL/min
Increases in blood ammonia levels would be expected in which of the following conditions:
End-stage cirrhosis
Which of the following is considered the major transport protein for vitamin A?
Retinol-binding protein
Serum Iron (SI)
SI is a measure of circulating iron bound to transferrin and is reflective of total body iron. SI is elevated in HH and acute hepatitis. SI is decreased in iron deficiency anemia and chronic inflammation.
A 67-year-old homeless man was seen in the ambulatory clinic for chest pain and sputum production. A mycobacterial culture showed the following: rough, non-pigmented colonies, which grew after two weeks at 35oC and failed to grow at other temperatures, serpentine cording, a strongly positive niacin test, nitrate reduction, and loss of catalase activity after heating at 68oC in pH 7. What is the most likely identification?
The correct choice is Mycobacterium tuberculosis. It is the only Mycobacterium species listed that is niacin positive.
Which of the following is currently considered to be a good test for screening persons for hereditary hemochromatosis (HH) due to its sensitivity and specificity for iron overload?
The most widely used test for screening for HH is transferrin saturation due to its sensitivity and specificity for iron overload. A transferrin saturation result of >45% is diagnostic for HH.
According to the Michaelis-Menton kinetics theory, when a reaction is performed in zero-order kinetics:
The substrate concentration is in excess and the reaction rate is dependent on the enzyme concentration
All of the following are quantitative methods for the determination of albumin EXCEPT?
The sulfosalicylic acid method is a semiquantitative method and not a quantitative method. It is also not specific for albumin. All of the others are quantitative methods for the determination of albumin.
A urine concentration test was performed on a patient after a fluid intake deprivation period with the following findings: After 12 hours Urine Osmolality = 850 mOsm/KgAfter 16 hours Urine Osmolality = 850 mOsm/Kg
This represents normal kidney function.
All of the following are methods employed for measuring the specific gravity of urine, EXCEPT?
UIBC represents the portion of iron binding sites on transferrin that are not occupied by iron. Therefore, a low UIBC indicates that transferrin is highly saturated with iron, a finding consistent with hereditary hemochromatosis (HH).
Which one of the following proteins in cerebrospinal fluid (CSF) is used to monitor the integrity of the blood-brain barrier?
albumin
Which of the following tumor markers is associated with testicular cancer?
beta hCG, or Human chorionic gonadotropin = Testicles
Vitamin D is formed in the skin and hydroxylated in two places before it is in its active form of 1,25-dihydroxy vitamin D. Where does the second hydroxylation occur?
kidneys
Flow cytometry is a useful tool in the study all of the following disorders, EXCEPT?
viral hepatitis
The National Heart, Lung, and Blood Institute (NHLBI) and American Heart Association (AHA) have created a set of parameters to define the presence of metabolic syndrome. Select the set of laboratory assays that are utilized in the NHLBI and AHA criteria for metabolic syndrome diagnosis.
Fasting blood glucose, triglycerides, HDL-C
Alpha Fetoprotein (AFP)
Hepatocellular carcinoma (a liver biopsy of a hepatocellular carcinoma is shown in the image) Germ cell and yolk sac tumorsMetastatic carcinomas of the liver
Which of the following is the most common technique that is used by clinical laboratories for therapeutic drug monitoring?
Immunoassay
Which of the following tests confirms the presence of Bence-Jones proteinuria:
Immunoelectrophoresis
In healthy individuals, calcitonin is synthesized by which cells in the body?
In healthy individuals, calcitonin is only synthesized by the thyroid C cells
A routine laboratory workup is ordered for an outpatient. The patient's lipid results are as follows: Total cholesterol = 295 mg/dL HDL = 30 mg/dL Triglycerides = 200 mg/dL What is the LDL cholesterol level for this patient?
LDL cholesterol = Total cholesterol - (HDL + (Trig / 5)) In this case, the calculation for LDL would be: LDL cholesterol = 295 mg/dL - (30 mg/dL + (200 mg/dL / 5)) LDL cholesterol = 295 mg/dL - 70 mg/dL = 225 mg/dL
It is important to specify if a blood specimen is a capillary specimen rather than a venous specimen. How will the following laboratory results be affected if a capillary specimen is tested?
Potassium, calcium, and total protein are lower in capillary specimens, where glucose is typically higher than in venous blood.
Which of the following would you find in a primary hyperparathyroidism case?
Primary hyperparathyroidism is a disorder of the parathyroid glands where overactive parathyroid glands secrete too much parathyroid hormone (PTH). This excess PTH triggers the release of too much calcium into the bloodstream. The bones may lose calcium, and too much calcium may be absorbed from food. The levels of calcium may increase in the urine, causing kidney stones. PTH also lowers blood phosphorus levels by increasing the excretion of phosphorus in the urine.
When three tubes of cerebrospinal fluid are received in the laboratory they should be distributed to the various laboratory sections as follows:
#1 Chemistry, #2 Microbiology, #3 Hematology
Which of the following blood tests is used in the evaluation of hepatic disease?
Alanine aminotransferase (ALT or SGPT)
Which disease/condition is associated with a deficiency in thiamine?
Beriberi
Unconjugated bilirubin is conjugated in the liver with which of the following substances to become water-soluble?
Bilirubin is conjugated with glucuronic acid in the liver to become conjugated bilirubin, which is water-soluble. Conjugated bilirubin passes directly from the liver into the bile duct and then into the intestine where the bacteria reduce it into urobilinogen.
What changes in potassium and sodium serum results may occur with diuretic use?
Decrease in both.
Elevation of serum creatine kinase may be associated with:
Duchenne muscular dystrophy or cerebrovascular accident (stroke) or vigorous exercise.
A 3-year old girl was brought to the ER with a temperature of 103ºF, lethargy, and cervical rigidity. Three tubes of cloudy CSF were delivered to the Lab, and preliminary test results showed: WBC: 4,500/µL Differential: 88% neutrophilsGlucose: 15 mg/dL 12% lymphocytesProtein: 140 mg/dLGram stain: No organisms observed From these results, what preliminary diagnosis SHOULD the physician consider?
Due to the elevated white blood cell count along with a strong percentage of neutrophils, a bacterial infection should be suspected. Though there are no organisms seen on the gram stain, a bacterial infection is still very possible as the bacterial count in the spinal fluid may be low. A viral meningitis would be more closely associated with an increased quantity of lymphocytes. Brain tumors and subdural hematomas would not be associated with these laboratory findings.
Serum TSH levels five times the upper limit of normal in the presence of a low T4 and low T3 uptake could mean which of the following?
During primary hypothyroidism, where a defect in the thyroid gland is producing low levels of T3 and T4, the TSH level is increased. TSH is released in elevated quantities in an attempt to stimulate the thyroid to produce more T3 and T4 as part of a feedback mechanism. Primary hypothyroidism can occur extrinsically, due to conditions such as iodine deficiency, or intrinsically due to conditions such as Hashimoto thyroiditis.
Glucose is considered an aldose because:
It contains a terminal carbonyl group, called an aldehyde group.
Albuterol is a fast-acting bronchodilator used acutely during asthma attacks. All of the reasons below explain why therapeutic drug monitoring (TDM) for albuterol is not available or common, EXCEPT?
It has a narrow therapeutic window.
Cardiac Troponin I (cTnI)
It is measured as an early indicator of an AMI because it is usually released and detectable within 4 - 6 hours following myocardial damage and peaks around 24 hours. It remains elevated in peripheral blood 3 - 7 days and can be elevated as long as 14 days.
Which of the following best describes the benefits of the RPR or VDRL tests:
Monitoring course of treatment
Which of the following is the EARLIEST biochemical marker of myocardial infarction?
Myoglobin is found in elevated levels when muscle tissue is damaged but it lacks specificity. It does, however, respond very rapidly after myocardial infarctions and rises within 1-3 hours and it returns usually to normal levels within 24 hours, faster than CK, troponin, or LD.
Myoglobin
Myoglobin is used infrequently as a cardiac biomarker. It is released earlier after muscle injury than cardiac troponins and CK-MB and returns to normal faster than either of these other markers. It rises within 2-4 hours after chest pain, peaks in 6-12 hours, and is usually normal within 24-36 hours.Myoglobin is present in all muscle, not just cardiac muscle.
Prostate-Specific Antigen (PSA): Clinical Applications Examples of Tumor Markers: Enzymes
PSA has been widely and successfully used as a tumor marker for prostate cancer and has utility in: Early detection of prostate cancerStaging of prostate cancerMonitoring effectiveness of treatment Monitoring for recurrence
Transferrin (Tf) and Total Iron Binding Capacity (TIBC)
TIBC is performed in a 2-step method by adding ferric iron to the specimen in sufficient quantity to completely fill all of the iron binding sites on transferrin. Excess, unbound iron is removed by adsorption with magnesium carbonate, alumina, or ion resin. The iron content of the saturated binding protein is then measured as described for SI. In many analytical systems, TIBC is calculated based on measuring the unsaturated iron binding capacity (UIBC). (2)
Which assay is recommended by the American Heart Association (AHA) and the Centers for Disease Control and Prevention (CDC) as the inflammatory marker of choice in the evaluation of cardiac heart disease risk
The hs-CRP (high sensitivity C-reactive protein) assay detects CRP in very low levels. It is a measurement of chronic inflammation and is used in cardiac risk assessment.
Which of the following contributes to specific gravity but does NOT contribute to osmolality?
The presence of large amounts of protein and glucose will alter the specific gravity and should be considered when interpreting specific gravity results.
The ability of an instrument or testing method to provide a negative result for patients who do not have the disease or condition is known as:
The specificity of a test refers to its ability to provide a negative reaction for patients who do not have the disease or condition. In other words, this is a way to determine how well a testing method can rule out other conditions or similar analytes.
Which of the following is considered a cause of hypomagnesemia (decreased levels of magnesium in the blood)?
There are many reasons why a patient would develop hypomagnesemia such as reduced intake, decreased absorption, and increased excretion. Pancreatitis will cause decreased absorption of magnesium leading to hypomagnesemia.