MLT GlobeASCP exam preparation (USA · MLS / MLT) – page 47
1200 practice MCQs for the ASCP medical laboratory exam. Level: Advanced.
An adult man has an HDL cholesterol of 30 mg/dL (0.78 mmol/L). How is this result interpreted?
An HDL cholesterol below 40 mg/dL (1.0 mmol/L) is classified as low and is a recognised risk factor for coronary heart disease.
An adult's LDL cholesterol is 195 mg/dL (5.0 mmol/L). By NCEP ATP III categories this is:
NCEP ATP III classifies LDL of 190 mg/dL (4.9 mmol/L) or more as very high. Optimal is below 100 mg/dL and borderline high is 130–159 mg/dL.
A patient forgot to fast before a lipid profile. Which result is least affected by the recent meal?
Total cholesterol changes very little after a meal, whereas triglycerides and chylomicrons rise, and Friedewald LDL is calculated from triglycerides so it is also affected.
A patient arrives 1 hour after chest pain began. The first high-sensitivity troponin is within the reference range. What is the correct next step?
Troponin may not yet be raised soon after symptom onset. Serial measurements are needed to detect a rise and/or fall that confirms myocardial injury.
Enzyme A has a Km of 0.1 mmol/L and enzyme B has a Km of 5 mmol/L for the same substrate. Which statement is correct?
Km is the substrate concentration at half-maximal velocity. A lower Km means half-maximal rate is reached at a lower substrate level, indicating higher affinity.
A man with long-term heavy alcohol use has low serum albumin and a prolonged prothrombin time that does not correct with vitamin K. This best reflects:
Low albumin and a PT not corrected by vitamin K indicate that the liver cannot make proteins and clotting factors, as in cirrhosis. In obstruction, PT usually corrects with vitamin K.
A patient taking a loop diuretic (furosemide) for heart failure has serum potassium of 3.0 mmol/L. The most likely cause is:
Loop diuretics increase sodium delivery to the distal nephron, promoting renal potassium excretion and hypokalemia. Hemolysis and EDTA contamination cause falsely high potassium.
An elderly patient with poor fluid intake has serum sodium of 156 mmol/L. This is best described as:
A sodium above 145 mmol/L is hypernatremia. In elderly patients with reduced thirst or access to water, loss of water relative to sodium is the usual cause.
A patient with advanced chronic kidney failure is most likely to have which acid-base disorder?
Failing kidneys cannot excrete daily acid or regenerate bicarbonate, so bicarbonate falls and metabolic acidosis develops.
A patient with Addison disease (primary adrenal insufficiency) is most likely to show which electrolyte pattern?
Lack of aldosterone reduces sodium reabsorption and potassium excretion, giving hyponatremia and hyperkalemia. High sodium with low potassium is typical of aldosterone excess.
A woman with iron deficiency anemia starts oral iron. Which is the earliest laboratory sign of response, usually seen within about 1 week?
The marrow responds quickly, and reticulocytes rise within about 5–10 days. Hemoglobin takes weeks to normalise, and ferritin refills stores only after months.
A vancomycin 'trough' level was drawn through the same IV line immediately after the dose was infused. The result will most likely be:
Drawing from the infusion line right after a dose contaminates the sample with drug and misses the true trough time, giving a falsely high level. Troughs are drawn just before the next dose from a different site.
A 2-month-old baby of an HIV-positive mother has a positive HIV antibody test. Why does this not confirm infection in the baby?
Maternal IgG crosses the placenta and can persist for up to 18 months, so infant diagnosis uses nucleic acid tests (HIV DNA or RNA) instead of antibody tests.
A young woman has a butterfly facial rash, joint pain, a positive ANA and anti-dsDNA antibodies. The most likely diagnosis is:
Malar rash, arthritis, a positive ANA and anti-dsDNA (highly specific) together strongly point to SLE.
In type III hypersensitivity, tissue damage is caused mainly by:
Immune complexes deposit in vessel walls, glomeruli and joints, activate complement and attract neutrophils, which cause the damage, as in serum sickness and lupus nephritis.
A boy from an endemic area has blood at the end of urination. Urine microscopy shows large oval eggs with a terminal spine. The parasite is:
Schistosoma haematobium lives in the veins of the bladder and passes terminal-spined eggs in urine, causing terminal hematuria. S. mansoni eggs have a lateral spine and are found in stool.
A patient has 50 red cells per HPF with normal, uniform shape and no red cell casts or protein. The bleeding most likely comes from:
Uniform (isomorphic) red cells without red cell casts or proteinuria suggest non-glomerular bleeding, for example from stones, infection or tumour anywhere from the renal pelvis to the urethra. Glomerular bleeding gives dysmorphic red cells, red cell casts and often proteinuria.
CSF from an elderly adult with bacterial meningitis shows Gram-positive lancet-shaped diplococci. The most likely organism is:
Streptococcus pneumoniae is a Gram-positive lancet-shaped diplococcus and the commonest cause of bacterial meningitis in adults. N. meningitidis is Gram-negative and H. influenzae is a Gram-negative coccobacillus.
A semen sample has normal volume but a sperm concentration of 5 million/mL. How is this described?
A concentration below the WHO lower reference limit (16 million/mL in the 2021 manual) is oligozoospermia. Azoospermia is no sperm, and asthenozoospermia refers to poor motility.
An infant has watery diarrhea after milk feeds, and the stool gives a positive copper-reduction (Clinitest) test for reducing substances. This most suggests:
Unabsorbed sugars such as lactose reach the stool and give a positive reducing substances test, pointing to carbohydrate (e.g. lactase) deficiency.