MLT GlobeMOH exam preparation (UAE) – page 28
700 practice MCQs for the MOH medical laboratory exam. Level: Basic to intermediate.
CSF left standing forms a delicate web-like clot (pellicle). Cell count shows lymphocytes, glucose is low and protein is markedly raised. This most suggests:
TB meningitis typically has lymphocytes, low glucose, very high protein and a pellicle from fibrinogen. Viral meningitis has normal glucose, and Guillain–Barré shows high protein with few cells.
After head trauma, a patient has clear fluid dripping from the nose. Which laboratory test best confirms that the fluid is CSF?
Beta-2 transferrin is found in CSF and perilymph but not in nasal secretions or blood, making it a specific marker for CSF leak. Glucose dipsticks give false positives from nasal mucus or blood.
According to the WHO 2021 manual, the lower reference limit for sperm concentration is:
WHO 2021 gives 16 × 10⁶/mL as the 5th percentile for sperm concentration. The value 39 million is the lower limit for total sperm number per ejaculate, not concentration.
The reagent strip specific gravity pad measures:
Ions in urine release hydrogen ions from a polyelectrolyte, changing the pH indicator colour. Non-ionic solutes such as glucose and radiographic contrast are not detected.
A woman with fever, flank pain and pyuria has white blood cell casts in her urine. This finding helps distinguish:
WBC casts form inside renal tubules, showing that the inflammation involves the kidney (pyelonephritis or interstitial nephritis). Cystitis produces WBCs without casts.
Rouleaux cause false positives at immediate spin but usually not in the antiglobulin phase because:
Rouleaux depend on abnormal plasma proteins. Washing removes them before AHG, so the AHG reading is unaffected.
A strong antibody gives weak reactions in undiluted plasma but strong reactions at 1:8 and 1:16. This is called:
In prozone, antibody excess blocks lattice formation; dilution restores agglutination. Postzone is antigen excess.
Glycerol must be removed from frozen red cells before transfusion because, if infused, it would:
Glycerol-loaded cells are hypertonic; placed directly into plasma, water rushes in and they lyse. Stepwise washing with decreasing saline concentrations removes glycerol safely.
A red cell unit is returned unused to the blood bank 40 minutes after issue. It may be reissued if:
Returned units may re-enter inventory only if the container was not entered and the temperature was kept within limits (commonly 1–10 °C) according to validated procedures. A fixed time rule alone is not enough.
In US areas at risk, blood donations are screened by nucleic acid testing for which tick-borne parasite?
Babesia microti is transmitted by Ixodes ticks and causes transfusion-transmitted babesiosis. FDA guidance requires NAT screening of donations in affected regions. T. cruzi is screened by antibody.
A group O, D-negative woman carries a group A, D-positive fetus. Why is her risk of forming anti-D reduced?
ABO-incompatible fetal cells entering the maternal circulation are quickly destroyed by maternal anti-A or anti-B, so there is less chance of immunization to D.
An infant treated for Rh HDFN is discharged. Three weeks later, hemoglobin is very low with low reticulocytes. The most likely cause is:
Maternal antibody can persist for weeks and continue to destroy red cells, while erythropoiesis is suppressed after transfusions. Infants need hemoglobin monitoring for several weeks.
The Le(a−b−) phenotype is most common in people of:
About a fifth of people of African descent are Le(a−b−), compared with about 6% of Europeans.
At booking, a D-negative woman who has never received RhIG has anti-D with a titer of 64. Regarding RhIG, the correct action is:
RhIG prevents primary immunization but cannot reverse it. A high titer with no RhIG history means immune anti-D, which needs HDFN monitoring instead.
Red cells react very strongly with anti-D but not with anti-C, anti-c, anti-E or anti-e. This phenotype is:
D−− cells lack CcEe and show exalted D. Immunized people make anti-Hr0 and need D−− blood. Rhnull cells lack D as well.
How long does full renal compensation for a primary respiratory acid-base disorder usually take?
Kidneys adjust H+ excretion and bicarbonate reabsorption slowly, reaching full compensation over several days. Respiratory compensation for metabolic disorders begins within minutes to hours.
In what form is most carbon dioxide transported in the blood?
About 70% of CO2 is carried as bicarbonate formed in RBCs by carbonic anhydrase; about 20–25% is bound to hemoglobin as carbamino compounds and 5–10% is dissolved.
What does lecithin-cholesterol acyltransferase (LCAT) do in plasma?
LCAT transfers a fatty acid from lecithin to free cholesterol, forming cholesteryl ester that moves into the HDL core. This is a key step in reverse cholesterol transport. Transfer to VLDL is done by CETP.
Calculate the APRI score: AST 80 U/L (upper limit 40 U/L), platelets 100 × 10⁹/L. [APRI = (AST ÷ AST ULN) ÷ platelets (10⁹/L) × 100]
APRI = (80 ÷ 40) ÷ 100 × 100 = 2.0. In chronic viral hepatitis, an APRI above 2.0 suggests cirrhosis (WHO).
A patient with epilepsy on valproate becomes drowsy and confused. Plasma ammonia is high while aminotransferases, bilirubin and INR are normal. The most likely cause is:
Valproate can inhibit the urea cycle (via reduced N-acetylglutamate) and cause hyperammonemic encephalopathy without liver damage. Normal INR and enzymes argue against liver failure.