MLT GlobeSCFHS exam preparation (Saudi Arabia) – page 13
749 practice MCQs for the SCFHS medical laboratory exam. Level: Intermediate.
Basophil granules are rich in which substances?
Basophil granules contain histamine and heparin, which are released in allergic reactions.
A 'shift to the left' in the differential count means:
A left shift means more young neutrophil forms (bands, metamyelocytes, sometimes myelocytes) in the blood, typically in bacterial infection.
Natural killer (NK) cells are usually identified by which surface marker?
NK cells are CD56-positive (often CD16-positive) and CD3-negative. CD19 marks B cells, CD3 T cells and CD34 immature progenitor cells.
Bence Jones proteins found in the urine of myeloma patients are:
Bence Jones proteins are free kappa or lambda light chains made by the plasma cell clone. They are small enough to pass the glomerulus into urine.
In multiple myeloma, the most common type of monoclonal immunoglobulin is:
IgG myeloma is the most common, followed by IgA. A monoclonal IgM usually points to Waldenström macroglobulinemia rather than myeloma.
On a stained blood smear, normal platelets measure about:
Platelets are small cell fragments about 2–3 µm across, much smaller than a red cell (7–8 µm).
A platelet count of 650 × 10^9/L in an adult is described as:
The adult platelet reference interval is roughly 150–400 × 10^9/L, so 650 × 10^9/L is thrombocytosis.
Thromboxane A2 released by activated platelets mainly causes:
Thromboxane A2, made through the cyclooxygenase pathway, recruits and aggregates more platelets and constricts vessels. Aspirin blocks its production.
In immune thrombocytopenia (ITP), the platelet count is low mainly because:
In ITP, autoantibodies coat platelets, which are then removed by splenic macrophages. Marrow megakaryocytes are normal or increased.
Coagulation factor I is:
Factor I is fibrinogen, factor II prothrombin, factor III tissue factor and factor IV calcium.
Light-blue sodium citrate tubes for coagulation tests are designed to give a blood-to-anticoagulant ratio of:
Coagulation tubes are filled to give 9 parts blood to 1 part 3.2% citrate. The 4:1 ratio is used for the Westergren ESR.
Hemolytic anemia is anemia caused by:
In hemolytic anemia, red cells are destroyed before their normal 120-day lifespan, and the marrow cannot keep up.
Compared with adult HbA, fetal hemoglobin (HbF) has:
HbF (α2γ2) binds 2,3-BPG poorly, so it holds oxygen more tightly. This helps the fetus take oxygen from maternal blood.
Leaving a tourniquet on for several minutes before venipuncture can cause:
Long tourniquet time pushes fluid out of the vein, concentrating cells and large molecules. Tourniquets should stay on for no more than about 1 minute.
Landsteiner's rule states that:
Landsteiner's rule: healthy people have anti-A and/or anti-B against the ABO antigens they lack. For example, a group A person has anti-B.
Naturally occurring anti-A and anti-B usually become detectable at about what age?
Infants begin making their own ABO antibodies at about 3–6 months. This is why reverse grouping is not done on newborns.
The older term 'Du' refers to what is now called:
'Du' was the old name for red cells with weakened D expression, now called weak D.
Which maternal antibody is most likely to cause HDFN?
Anti-K is IgG and can cause severe fetal anemia. Anti-Lea, anti-P1 and anti-I are usually IgM, and the Lewis, P1 and I antigens are poorly developed on fetal red cells.
An antigen present on the red cells of almost all people is called a:
High-prevalence antigens occur in over 99% of people. Patients with antibodies to them are hard to supply with compatible blood.
Polyspecific antihuman globulin (AHG) reagent contains antibodies to:
Polyspecific AHG contains anti-IgG and anti-C3d, so it detects red cells coated with IgG, complement or both.