MLT GlobeQCHP exam preparation (Qatar) – page 5
749 practice MCQs for the QCHP medical laboratory exam. Level: Intermediate.
The usual reference interval for total protein in lumbar cerebrospinal fluid of an adult is about:
Adult lumbar CSF protein is roughly 15–45 mg/dL, less than 1% of serum protein (6–8 g/dL). Neonates have higher normal values.
A 19-year-old with liver disease and a neurological tremor has low serum ceruloplasmin. This most suggests:
Wilson disease (ATP7B defect) impairs copper incorporation into ceruloplasmin, so serum ceruloplasmin is usually low, with liver and neurological disease. Hemochromatosis is an iron disorder.
The main analytical advantage of enzymatic creatinine methods over the Jaffe method is:
Enzymatic (creatininase-based) methods are more specific and are less affected by pseudo-chromogens such as ketones, glucose and some cephalosporins. They are usually more expensive than Jaffe methods.
Current KDIGO guidance recommends estimating GFR in adults with which equation?
KDIGO recommends CKD-EPI creatinine-based eGFR for adults; the 2021 race-free version is now widely adopted. Schwartz is for children, and Cockcroft-Gault estimates clearance, mainly for drug dosing.
N-acetylcysteine is effective in acetaminophen overdose because it:
The toxic metabolite NAPQI is normally conjugated with glutathione. NAC replenishes glutathione and protects the liver. Fomepizole, not NAC, inhibits alcohol dehydrogenase.
When collecting blood for a legal blood alcohol test, the site should be cleaned with:
Alcohol-based swabs can contaminate the sample and falsely raise the result. A non-alcohol antiseptic and a sealed tube, with chain of custody, are used.
Which test best reflects a person's vitamin D status?
25-OH vitamin D has a long half-life and reflects body stores. 1,25-(OH)2 D is tightly regulated and may be normal or even high in deficiency.
Serum alpha-fetoprotein (AFP) is most useful as a marker for:
AFP is made by fetal liver and yolk sac, and it rises in hepatocellular carcinoma and nonseminomatous germ cell tumors. CA-125 is used for ovarian epithelial cancer.
A raised maternal serum AFP at 16–18 weeks of pregnancy is most associated with:
Fetal AFP leaks into amniotic fluid and maternal blood through an open neural tube defect. Down syndrome is usually associated with a LOW maternal AFP.
In flow cytometry, forward scatter and side scatter mainly indicate, respectively:
Light scattered at low angles (forward) relates to cell size, while light scattered at 90 degrees (side) relates to granules and internal structure. Antigen density is measured by fluorescence.
The main role of glucose-6-phosphate dehydrogenase (G6PD) in red cells is to:
G6PD is the first enzyme of the hexose monophosphate shunt and generates NADPH, which keeps glutathione reduced to protect hemoglobin from oxidants. ATP comes from the Embden-Meyerhof pathway, not the shunt.
Which plasma test result is typically DECREASED in intravascular hemolysis?
Haptoglobin binds free hemoglobin and the complex is rapidly cleared by the liver, so the level falls. LDH, unconjugated bilirubin and free hemoglobin all rise in hemolysis.
In the sickle cell solubility test, a positive result appears as turbidity because:
Sodium dithionite deoxygenates hemoglobin, and deoxy-HbS polymerizes and is insoluble in concentrated phosphate buffer, making the solution cloudy. Saponin only lyses the cells; it does not agglutinate them.
A well 5-year-old develops petechiae 2 weeks after a viral illness. Platelets are 12 × 10^9/L; Hb, WBC and smear are otherwise normal. The most likely diagnosis is:
Childhood ITP often follows a viral infection and shows isolated thrombocytopenia. Leukemia and aplastic anemia usually affect other cell lines.
In light transmission aggregometry, platelet aggregation is detected as:
As platelets clump in stirred PRP, the plasma clears and more light passes through. Platelet-poor plasma serves as the 100% transmission reference.
Hemoglobin is 9.0 g/dL (90 g/L) and the RBC count is 3.0 × 10^12/L. What is the MCH?
MCH (pg) = Hb (g/dL) × 10 ÷ RBC (× 10^12/L) = 90 ÷ 3.0 = 30 pg. 10 pg comes from forgetting to multiply the hemoglobin by 10.
Which laboratory test is the earliest to become abnormal as body iron stores are depleted?
Ferritin falls first because it reflects storage iron. Serum iron and transferrin saturation fall later (iron-deficient erythropoiesis), and Hb and MCV fall last when anemia develops.
The typical bone marrow change in megaloblastic anemia is:
Impaired DNA synthesis delays nuclear development while hemoglobinization of the cytoplasm continues, giving large cells with open 'young' chromatin and mature cytoplasm (nuclear–cytoplasmic asynchrony).
Which antibiotic is classically associated with idiosyncratic aplastic anemia?
Chloramphenicol causes a dose-related reversible marrow suppression and a rare, often fatal, idiosyncratic aplastic anemia. The other antibiotics are not classic causes.
According to WHO, anemia in a non-pregnant adult woman is defined as a hemoglobin below:
WHO thresholds are <130 g/L for adult men, <120 g/L for non-pregnant women and <110 g/L for pregnant women.