MLT GlobeASCP exam preparation (USA · MLS / MLT) – page 45
1200 practice MCQs for the ASCP medical laboratory exam. Level: Advanced.
Which condition is most likely to produce ascites with a low serum–ascites albumin gradient (below 1.1 g/dL or 11 g/L)?
A low gradient means the ascites is not due to portal hypertension, as in peritoneal carcinomatosis, tuberculous peritonitis or pancreatitis. Cirrhosis, heart failure and Budd–Chiari syndrome give a high gradient.
A man had a vasectomy 12 weeks ago. Which post-vasectomy semen result allows him to stop other contraception?
Success requires azoospermia or only rare non-motile sperm (below about 100,000/mL); any motile sperm means the procedure has not yet worked. WHO reference limits for fertility do not apply here.
A patient on a diet containing about 100 g fat per day collects stool for 72 hours. The fecal fat is 18 g/day. The best interpretation is:
On a 100 g/day fat diet, excretion above 7 g/day indicates steatorrhoea from maldigestion or malabsorption. Lactose intolerance is shown by reducing substances, not fecal fat.
For the sweat chloride test, sweating is stimulated by:
Pilocarpine is driven into the skin with a small electric current, causing local sweating that is collected by filter paper or a plastic collection coil. Whole-body heating is unsafe and unstandardised.
A woman taking phenazopyridine for dysuria has bright orange urine. How does this affect reagent strip testing?
Phenazopyridine gives an orange pigment that can produce atypical colours on pads such as bilirubin, nitrite, ketone, protein and urobilinogen. Results should be confirmed by other methods.
A urine glucose pad is strongly positive, but blood glucose is normal and a repeat urine collected in a new container is negative. The first container was probably contaminated with:
Strong oxidising agents react with the chromogen directly, causing false-positive glucose (and blood) results. Ascorbic acid causes false negatives.
A pregnant woman has 2+ urine glucose on a reagent strip, but her fasting plasma glucose is 4.8 mmol/L (86 mg/dL). The most likely explanation is:
Glucose appears in urine when plasma glucose exceeds the renal threshold (about 160–180 mg/dL, 8.9–10 mmol/L); in pregnancy and renal glycosuria the threshold is lower. Ascorbic acid would cause a false negative.
A urine collected in a container rinsed with a quaternary ammonium disinfectant is likely to show a false-positive result on the:
Quaternary ammonium compounds and chlorhexidine alter the protein pad's indicator and give false-positive protein. Glucose false positives are caused by oxidising agents.
A refrigerated urine is tested immediately after removal from the refrigerator. Which result is most likely to be affected?
Cold slows enzymatic reactions, so refrigerated urine should reach room temperature before strip testing. Refrigeration does not create nitrite.
Yellow-brown spheres with concentric circles and radial striations are seen in the urine of a patient with severe liver disease. They are most likely:
Leucine forms oily yellow spheres with concentric and radial lines, seen with tyrosine in severe liver disease. Ammonium biurate spheres have spiky projections and occur in alkaline urine.
Three days after a haemolytic transfusion reaction, yellow-brown granules are seen free and inside cells in the urine sediment. Which stain confirms they are haemosiderin?
Haemosiderin (iron) stains blue with Prussian blue and appears in urine 2–3 days after intravascular haemolysis. Sudan III is used for fat.
Which epithelial cell, when seen in increased numbers in urine sediment, is the most clinically significant sign of kidney damage?
Renal tubular epithelial cells come from the nephron, so increased numbers indicate tubular injury such as ATN or toxicity. Squamous cells usually reflect contamination.
Highly refractile round structures with a central dimple show a 'Maltese cross' under polarised light. The patient's urine was collected by a nurse wearing powdered gloves. These are most likely:
Starch granules from glove powder also show a Maltese cross but have a dimpled centre and are irregular. Fat droplets are smooth, variable in size and stain with Sudan III.
How does serum erythropoietin (EPO) usually differ between secondary polycythemia due to chronic hypoxia and polycythemia vera (PV)?
In hypoxia-driven secondary polycythemia the kidney makes more EPO, so levels are normal or high. In PV the clone grows independently of EPO, and feedback suppresses EPO to low levels.
In iron deficiency anemia, the serum soluble transferrin receptor (sTfR) level is typically:
Iron-starved erythroid cells express more transferrin receptors, so sTfR rises in iron deficiency. In anemia of chronic inflammation it is usually normal, which helps separate the two.
A thin blood film shows small ring forms inside red cells and a few tetrads arranged like a Maltese cross, with no pigment or gametocytes. The most likely organism is:
Babesia forms small rings and a tetrad (Maltese cross) and makes no malaria pigment or gametocytes. Trypanosomes live outside red cells.
Howell-Jolly bodies are common in adults with sickle cell anemia mainly because:
Repeated infarcts cause autosplenectomy, so the spleen can no longer remove nuclear remnants (Howell-Jolly bodies) from red cells.
A WBC count is 3.0 × 10^9/L with 60% lymphocytes, giving an absolute lymphocyte count of 1.8 × 10^9/L. The best description is:
The lymphocyte percentage is high, but the absolute count (1.8 × 10^9/L) is within the adult reference range. So this is a relative lymphocytosis, usually due to low neutrophils.
About half of the neutrophils inside blood vessels are loosely attached to vessel walls and are not counted in a blood sample. This group is called the:
Intravascular neutrophils are split into circulating and marginating pools of about equal size. Stress or exercise moves marginated cells into circulation and raises the count.
An absolute basophilia on the blood film is most characteristic of:
Basophilia is a typical feature of CML and other myeloproliferative neoplasms. Bacterial infection causes neutrophilia, not basophilia.