Important Clinical chemistry questions for the SCFHS and the Board examinations in both the USA and UK.
Important Clinical chemistry questions for the SCFHS and the Board examinations in both the USA and UK.
Choose the most appropriate single answer.
1. A patient has polyuria and polydipsia with a urine specific gravity of >1.040. Of the following possibilities, what is the most likely diagnosis?
a. Alcohol intoxication
b. ADH suppression from barbiturates
c. Diabetes mellitus
d. Li toxicity causing nephrogenic diabetes insipidus
e. Central ADH deficiency
(c) Polyuria is a condition defined as excessive or abnormally large production or passage of urine (greater than 2.5or 3L over 24 hours in adults). Polydipsia is excessive thirst or excess drinking. Diabetes is characterized by excessive thirst and water intake. Diabetes insipidus produces a dilute urine while mellitus produces a concentrated urine (high specific gravity). Glucosuria, as it occurs in diabetes, will also increase the specific gravity.
d. Oxidized glutathione
3. Synovial fluid from patients with gout typically contains
a. Uric acid crystals.
b. Calcium oxalate crystals.
c. Hippuric acid crystals.
d. Tyrosine crystals.
e. Triple phosphate crystals.
4. Water reabsorption from the renal tubules is stimulated by
(b) Antidiuretic hormone (ADH; vasopressin) stimulates water reabsorption in the kidney tubules. This is the major control mechanism for osmolality. Relaxin is a hormone produced by the ovary and the placenta with important effects in the female reproductive system and during pregnancy. In preparation for childbirth, it relaxes the ligaments in the pelvis and softens and widens the cervix. Secretin, a digestive hormone secreted by the wall of the upper part of the small intestine (the duodenum). Rennin enzyme also called chymosin protein-digesting enzyme that curdles milk by transforming caseinogen into insoluble casein. Oxytocin hormone neurohormone in mammals, the principal functions of which are to stimulate contractions of the uterus during labour and stimulate the ejection of milk (letdown) during lactation.
5. The excretion of delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) in urine is increased in which of the following?
a. ALA dehydratase deficiency
b. Acute intermittent porphyria
c. Porphyria cutanea tarda
6. What is a normal fasting blood glucose level in mmol/L?
a. 1.9 – 3.5 mmol/L
b. 3.9 – 5.5 mmol/L
c. 4.5–7.2 mmol/L
d. Less than 7.8 mmol/L
7. What happens when human urine stands for a long time in room temperature?
a. Creatinine increased
b. Urea decreased
c. PH not changed
d. Glucose increased
(b) Changes that may take place in a urine specimen if it is allowed to stand at room temperature for more than 1 hour. Bacteria turn urea to ammonia, changes the pH. May create false positive for protein. Bacteria multiply, makes specimen cloudy, increasing nitrite. Glucose will decrease; Microorgs use it as a source of food. Blood cells break down. Casts decompose.
8. Which of the following enzymes better used for diagnosis of acute pancreatitis?
(b) Serum amylase continues to be the most widely used test to diagnose acute pancreatitis, its popularity does not appear to be justified. The serum amylase test has a poor sensitivity and specificity. Recent studies indicate that serum lipase may be a better test to diagnose acute pancreatitis. Therefore, serum lipase should be used more frequently in the diagnosis of acute pancreatitis. Serum trypsin, although sensitive, is difficult to estimate and is not routinely available. Serum elastase offers no additional benefit over the serum amylase or lipase tests.
9. 25-hydroxycholecalciferol synthesis in
10. low density lipoprotein rich in
b. bile acids
(a) Low density lipoprotein (LDL) particles are the major cholesterol carriers in circulation and their physiological function is to carry cholesterol to the cells. LDL carries cholesterol from the liver to muscle and other tissues, and high density lipoprotein (HDL), carries cholesterol to the liver for conversion to bile acids.
11. Hypoglycemic hormone is
12. Half life time of albumin is
a. One week
b. 72 h
c. 48 h
d. 20 h
(d) Serum albumin is the serum albumin found in human blood. It is the most abundant protein in human blood plasma; it constitutes about half of serum protein. It is produced in the liver. It is soluble and monomeric. Albumin concentration in serum is approximately 35 - 50 g/L (3.5 - 5.0 g/dL).It has a serum half-life of approximately 20 days. It has a molecular mass of 66.5 kDa.
13. Heinz body testing is useful in the diagnosis of which of the following?
a. Quantitative hemoglobin disorders
b. Unstable hemoglobin disorders
c. High-oxygen-affinity hemoglobins
e. Hereditary persistence of Hb F
(b) Heinz bodies are precipitates of unstable hemoglobin that accumulate in the red cell and can be detected by supravital staining. These inclusions act to shorten red cell life span and enhance premature red cell removal by the spleen. Heinz bodies are not seen in thalassemias or persistence of Hb F. Methemoglobinemia is characterized by patient cyanosis resulting from an excess of deoxygenated hemoglobin in the red cell. High-oxygen-affinity hemoglobins usually result from structural abnormalities in hemoglobin that lead to decreased release of oxygen, also resulting in cyanosis. Neither methoglobinemia nor high-affinity hemoglobin is associated with Heinz body formation.
14. Which is an example of a macrovascular complication of poorly controlled diabetes?
a. Decreased sensation
c. Renal disease
15. What is angiotensin?
a. A hormone whose function is to communicate signals which control blood pressure.
b. A molecule produced in the kidney as a hormone precursor.
c. A hormone that signals blood vessels to expand.
d. A hormone that prevents kidney tubules from concentrating the urine.
16. When can persistent microalbuminuria be diagnosed?
a. When two consecutive urine specimens collected over 48 hours are abnormal for albumin.
b. When two of three urine specimens collected within a three- to six-month period are abnormal for albumin.
c. When a 24-hour urine specimen collected after a one-week restricted-protein diet is abnormal for albumin.
d. When two of three abnormal urine specimens for albumin are obtained after all blood-pressure medications have been stopped for 72 hours.
17. When can microalbuminuria be said to be present?
a. When urinary albumin excretion is less than 30 mg/day
b. When urinary albumin excretion is greater than 300 mg/day
c. When urinary albumin excretion is between 30 to 300 mg/day
d. When urinary albumin is positive on a urine dipstick test
18. According to the American Diabetes Association (ADA) a Type I diabetic should be screened annually for microalbuminuria. When should this screening begin?
a. Three to six months after diagnosis
b. Immediately upon diagnosis
c. One year after diagnosis
d. Five years after diagnosis
19. What is the most common tool by which to detect the presence of massive acute UGI bleeding?
a. Geiger counter
b. BP cuff
c. The eyeball
d. Pulse oximeter
e. Mass spectrophotometer
20. In patients presenting with acute UGI bleeding, what is the first order of business?
a. Determining the site of bleeding
b. Determining the porphyrin level
c. Ordering a comprehensive metabolic profile laboratory test to check organ system functions
d. Preventing cardiovascular collapse
21. Why is it important to screen for microalbuminuria?
a. It can detect chronic kidney disease.
b. It can identify an increased risk of proliferative retinopathy.
c. It is the strongest independent risk factor of cardiovascular disease.
d. All of the above
(d) It is important to screen for microalbuminuria because it can detect chronic kidney disease, identify an increased risk of proliferative retinopathy, and it is the strongest independent risk factor of cardiovascular disease. It can also detect that treatment with an ACE inhibitor or A-II antagonist is effective in slowing progress to nephropathy.
22. Which of the following groups is NOT at increased risk for microalbuminuria and thus does not require routine screening?
d. Patients with a family history of cardiovascular disease
23. The syndrome of antidiuretic hormone secretion (SIADH) is characterized by
c. Urine sodium concentration <20 mmol/L
d. Urine osmolality lower than serum osmolality
24. BCR-ABL fusion gene is present in approximately 90% of patients with which type of cancer:
a. ALL (acute lymphocytic leukemia)
b. CLL (chronic lymphocytic leukemia)
c. CML (chronic myelogenous leukemia)
d. Hodgkin's lymphoma
e. AML (acute myelogenous leukemia)
(c) In the majority of patients with CML, transformation of a hematopoietic stem cell results from the Philadelphia chromosome, a translocation between genes 9 and 11. This creates the BCR-ABL fusion gene; the gene product is a tyrosine kinase that activates signaling pathways resulting in cell growth and proliferation.
25. Which Hb A1c percentage usually corresponds with a mean plasma glucose concentration of 100 mg/dL?
26. The predominate form of vitamin A is
a. Retinoic acid
d. Retinyl esters
27. Which of the following vitamins would be LEAST affected by long periods of fat malabsorption?
a. vitamin A
b. vitamin C
c. vitamin D
d. vitamin E
e. vitamin K
28. Serum calcium levels are
a. high in both primary and secondary hyperparathyroidism
b. high in primary and low in secondary hyperparathyroidism
c. high in secondary and low in primary hyperparathyroidism
d. low in both primary and secondary hyperparathyroidism
29. The principle source of energy for the body is
d. Simple sugar
e. None of the above
30. Drug screen for benzoylecgonine, positive alcohol and normal electrolytes. The patient's condition got worse in next hour when he started complaining of severe chest pain radiating to his arms in addition to profuse sweating. The clinical symptoms experienced by the patient is best explained by the effect of
a. Stimulatory effect of benzoylecgonine a cocaine metabolite
b. Excessive ethanol consumed by patient over short time period.
c. Cocaethylene production by the liver.
d. Atherosclerosis caused by excessive cocaine abuse.
e. Gamma Hydroxybutyric Acid (GHB) consumption
(c) Co-consumption of cocaine and ethanol results in formation of coca ethylene in liver, produced by the esterification of cocaine by ethanol. Cocaethylene blocks the reuptake of dopamine in the dopaminergic pathways more effectively than cocaine by itself. Additionally it causes pronounced vasocontriction of the coronary arteries and induces increased myocardial oxygen demand which in turn induces myocardial ischemia and myocardial infarction in some cases. Prolonged cocaine use has also been shown to promote atherosclerosis.
31. Most assays for hCG use a sandwich (immunometric) format. A laboratory offers two hCG assays in two different testing platforms, one of which is referred to as “tumor hCG”. What does that designation mean?
a. FDA approval for use as a tumor marker
b. It mostly detects the alpha subunit
c. Uses an antibody for the alpha and an antibody for the beta subunits
d. Equimolar detection of free alpha and beta subunits
e. It detects intact hCG and the free beta subunit
(e) There is no commercially available hCG assay approved by the FDA for use as a tumor marker. The National Academy of Clinical Biochemistry issued recommendations with the analytical standards for hCG assays used as tumor markers for monitoring testicular cancer patients. Assays that measure the intact form using an antibody for hCG alpha and another for hCG beta will fail to detect the free aeta subunit, which is heavily expressed by some cancer patients. The preferred assay is a total beta hCG assay, with equimolar detection of intact hCG and free hCG beta. Also, the assay must have a low detection limit and minimal cross-reactivity with other hormones (such as LH).
32. A 55 year-old woman presents to the internal medicine department complaining of numbness in her feet, pale skin, dizziness, extreme fatigue and weakness. Blood is drawn for a complete blood count (CBC), comprehensive metabolic panel (CMP) and hemoglobin A1C (HbA1C). The CBC results are normal except for low blood count, hematocrit and hemoglobin (8.5 g/dL). The CMP results show an elevated fasting plasma glucose (195 mg/dL), while her HbA1C is on the lower end of normal (4.5%). Which one of the following conditions is(are) most likely present in this patient?
b. Anemia and pre-diabetes
c. Anemia and diabetes
(c) The patient's symptoms are highly suggestive of anemia and diabetes. Her biochemical test results also support this except for the normal HbA1C (less than 5.7% normal). HbA1C results are unreliable in patients with hemoglobin variants, undergo blood transfusions, and conditions that impact red blood cell turnover, such as anemia. Therefore, fasting plasma glucose is the more reliable result in this patient. A FPG result greater than 126 mg/dL is defined as diabetic.
33. Calcium concentration in the serum is regulated by:
b. Parathyroid hormone
d. Vitamin C
34. Which of the following tests is useful for the diagnosis of neurosyphilis?
a. Treponema pallidum particle agglutination (TP-PA)
b. Rapid plasma regain (RPR)
d. Venereal disease research laboratory (VDRL) test
e. Flurescent treponemal antibody absorption (FTA-abs)
(d) The VDRL test is the oldest test for the diagnosis of neurosyphilis. While it is not particularly sensitive (approx. 30%), it is highly specific; it is the only assay recommended for testing CSF. RPR testing is even less sensitive in the matrix of CSF. Treponemal tests are not recommended for testing CSF.
35. Which of the following is not associated with neutrophilia?
a. Acute bacterial infections
b. Aplastic anemia due to total body irradiation
c. Cigarette smoking
d. Lithium therapy
e. Steroid therapy
(b) This question is intended to illustrate the importance of understanding the nomenclature of hemoglobinopathies and thalassemias. Hemoglobinopathies are hereditary disorders where a mutation in a globin gene results in the production of a mutant globin protein that can form abnormal hemoglobin, such as Hb S (“sickle” hemoglobin) or Hb C. A thalassemia is the result of a mutation that causes diminished production of 1 or more normal globin proteins that can result in decreased production of normal hemoglobins.
36. Which of the following is associated with basophilia?
a. A all acute infections
b. Acute viral syndromes that produce “mononucleosis-type blood picture”
c. Chronic myeloid leukemia
d. Steroid therapy
e. Artificial insemination
(c) Basophilia is unusual and is seen in a limited number of clinical settings including acute and chronic renal failure, hypothyroidism, and chronic myeloproliferative disorders. As there are several new therapeutic options for chronic myeloproliferative disorders, it is very important to be aware that basophilia can be an early indicator of one of these diseases.
37. An amino acid that yields acetoacetyl CoA during the catabolism of its carbon skeleton would be considered:
c. Glycogenic and ketogenic
d. Neither glycogenic nor ketogenic
(b) Ketogenic (we assume that it is the final product of the catabolism of this amino acid and no glucogenic metabolites are produced.) Ketogenics: Amino acids that yield acetyl CoA or acetoacetyl CoA ( e.g. they do not produce metabolites that can be converted in glucose). Lysine and Leucine are the only amino acids that are exclusively ketogenics. Glucogenic: Amino acids whose catabolism yields to the formation of Pyruvate or Krebs Cycle metabolites, that can be converted in glucose through gluconeogenesis
38. Myoglobin in the urine could be an indicator of what?
a. Body's hydration state
b. Breakdown of RBCs
c. Skeletal muscle injury
(c) Myoglobin is a small, oxygen-binding protein found in heart and skeletal muscle. When heart or skeletal muscle is injured, myoglobin is released into the blood. Myoglobin is filtered from the blood by the kidneys and is released into the urine. A urine test is ordered to evaluate myoglobin levels in people who have had extensive damage to their skeletal muscles (rhabdomyolysis). Urine myoglobin levels reflect the degree of muscle injury and, since myoglobin is toxic to the kidneys, reflect the risk of kidney damage.
39. Type 2 diabetes is characterized by:
a. Insulin resistance
b. Insulin lack
c. Beta cell destruction
d. None of the above
(a) Type 2 diabetes is a chronic condition in which the body fails to properly use and store glucose. Instead of converting sugar into energy, it backs up in the bloodstream and causes a variety of symptoms. Type 2 (formerly called 'adult-onset' or 'non insulin-dependent') diabetes results when the body doesn’t produce enough insulin and/or is unable to use insulin properly (this is also referred to as ‘insulin resistance’).
40. What laboratory test evaluates kidney function and is a breakdown product of protein?
b. SGTP (ALT)
(d) A common blood test, the blood urea nitrogen (BUN) test reveals important information about how well your kidneys and liver are working. A BUN test measures the amount of urea nitrogen that's in your blood. Blood urea nitrogen (BUN) is an indication of renal (kidney) health. The normal range is 1.8-7.1 mmol/L or 6–20 mg/dL.
41. Creatinine concentrations in serum are influenced by
a. Hydration level
b. Amylase concentration
c. Liver disease
d. Insulin Productions
(a) Creatinine is a breakdown product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body. A higher than normal level may be due to: Blocked urinary tract. Kidney problems, such as kidney damage or failure, infection, or reduced blood flow. Loss of body fluid (dehydration). Muscle problems, such as breakdown of muscle fibers (rhabdomyolysis). Problems during pregnancy, such as seizures caused by eclampsia or high blood pressure caused by preeclampsia.
42. An increase in unconjugated bilirubin may be the result of
a. Either hepatic or posthepatic failure
b. Either hepatic or biliary failure
c. Either prehepatic or posthepatic failure
d. Either hepatic or prehepatic failure
(d) Unconjugated bilirubin: A fat-soluble form of bilirubin that is formed during the initial chemical breakdown of hemoglobin and, while being transported in the blood, is mostly bound to albumin. Unconjugated hyperbilirubinemia can result from increased production, impaired conjugation, or impaired hepatic uptake of bilirubin.
43. What serum component can be used as a screening test for hypothyroidism?
c. Total protein
d. Creatine kinase
(b) Hypothyroidism is a condition in which the body lacks sufficient thyroid hormone. Your body needs thyroid hormones to make cholesterol and to get rid of the cholesterol it doesn’t need. When thyroid hormone levels are low (hypothyroidism), your body doesn’t break down and remove LDL cholesterol as efficiently as usual. LDL cholesterol can then build up in your blood.
44. What ion is important in regulating blood pH and in transporting carbon dioxide from the tissue to the lungs?
(d) The bicarbonate buffer system is an acid-base homeostatic mechanism involving the balance of carbonic acid (H2CO3), bicarbonate ion (HCO−3), and carbon dioxide (CO2) in order to maintain pH in the blood and duodenum, among other tissues, to support proper metabolic function. Catalyzed by carbonic anhydrase, carbon dioxide (CO2) reacts with water (H2O) to form carbonic acid (H2CO3), which in turn rapidly dissociates to form a bicarbonate ion (HCO−3 ) and a hydrogen ion (H+).
45. What ion increases with malignancy, particularly with lymphosarcoma?
(c) lymphosarcoma is a malignant tumor in lymphatic tissue, caused by the growth of abnormal lymphocytes. General signs and symptoms include depression, fever, weight loss, loss of appetite, loss of hair or fur and vomiting. Lymphoma is the most common cancerous cause of hypercalcemia (high blood calcium levels) in dogs.
46. EDTA plasma cannot be used for testing ……… plasma levels because EDTA forms a complex with it.
47. A good initial urinary screening test for suspected Cushings disease is
a. Endogenous ACTH
b. Low-dose dexamethasone supression test
c. ACTH stimulation
d. Cortisol/creatinine ratio
48. Determination of glycosylated hemoglobin is used for:
a. Assessing present glucose control
b. Assessing blood glucose control for the past 3 days
c. Assessing long-term( 2 - 4 month) blood glucose control
d. Adjusting daily insulin doses
49. Which of the following is NOT and indicator of dehydration:
a. High urine specific gravity
b. High cholesterol
c. High BUN
d. High hematocrit
(b) Dehydration is a deficit of total body water, with an accompanying disruption of metabolic processes by imbalance of sodium, potassium, chloride, and other electrolytes. Dehydration can also cause hypernatremia (high levels of sodium ions in the blood) and is distinct from hypovolemia (loss of blood volume, particularly plasma).
50. The recommended method for diabetes diagnosis is:
a. Oral glucose tolerance test
b. Fasting blood glucose
c. Post-prandial blood glucose
d. None of the above
(b) Fasting Plasma Glucose: This test checks your fasting blood glucose levels. Fasting means after not having anything to eat or drink (except water) for at least 8 hours before the test. This test is usually done first thing in the morning, before breakfast. Oral Glucose Tolerance Test: The OGTT is a two-hour test that checks your blood glucose levels before and 2 hours after you drink a special sweet drink. It tells the doctor how your body processes glucose. A 2-hour postprandial blood glucose test ("2 hour p.c. blood glucose test", etc.) measures blood glucose exactly 2 hours after eating a meal.