MLT GlobeDHA exam preparation (Dubai) – page 5
700 practice MCQs for the DHA medical laboratory exam. Level: Basic to intermediate.
Production of granulocytes and monocytes in the bone marrow is specifically termed:
Myelopoiesis covers granulocyte and monocyte formation from myeloid progenitors. Leukopoiesis is the broader term for all white cell production, including lymphopoiesis.
A patient grouped as AB has which naturally occurring ABO antibodies in plasma?
People lack antibodies to their own antigens. Group AB carries both antigens, so no anti-A or anti-B is formed, which is why AB plasma is the universal plasma donor.
An isolated platelet count of 35 × 10^9/L most typically presents with:
Thrombocytopenia causes mucocutaneous bleeding such as epistaxis, gum bleeding and petechiae. Deep bleeding into joints and muscles is typical of coagulation factor deficiency.
A positive direct antiglobulin test indicates:
The DAT adds anti-human globulin directly to washed patient cells, detecting in vivo sensitization. Free serum antibody is detected by the indirect antiglobulin test.
Circulating platelets normally survive for about:
Platelets circulate for roughly 7–10 days before removal by the spleen and liver. 120 days is the red cell lifespan.
Many red cell blood group antigens are membrane proteins carrying carbohydrate chains. Such proteins are called:
Glycoproteins such as glycophorins and band 3 dominate membrane proteins and carry antigens like MN. Lipoproteins transport lipids in plasma.
A battery-factory worker has anemia with coarse basophilic stippling of red cells. The most likely cause is:
Lead inhibits pyrimidine 5'-nucleotidase, so ribosomal RNA aggregates as coarse stippling, and it blocks heme synthesis. Stippling may also occur in thalassemia.
Normal red cells survive in the circulation for approximately:
Aged red cells are removed mainly by splenic macrophages after about 120 days. Shortened survival defines hemolysis.
Which total leukocyte count lies within the usual adult reference interval?
The adult WBC reference interval is roughly 4.0–11.0 × 10^9/L. Lower values indicate leukopenia and higher values leukocytosis.
Anemia is defined in the laboratory by:
Anemia means reduced oxygen-carrying capacity, measured as low hemoglobin. MCV classifies anemia but does not define it.
Which set of results favors iron deficiency anemia?
Iron deficiency lowers serum iron and ferritin while transferrin synthesis rises, increasing TIBC. Normal iron studies with microcytosis suggest thalassemia trait.
Christmas disease (hemophilia B) results from deficiency of:
Hemophilia B is X-linked factor IX deficiency, clinically similar to hemophilia A. Factor-specific assays distinguish them.
Which naturally occurring antibodies are expected in the plasma of a group O adult?
Group O red cells lack A and B antigens, so the plasma contains both anti-A and anti-B (plus anti-A,B), in keeping with Landsteiner's rule.
Which set of carbohydrate antigens belongs to the ABO (with H) system?
Group O cells carry unconverted H substance; there is no 'O antigen'. H is the precursor that the A and B transferases modify.
A prospective donor reveals a past confirmed positive anti-HIV result. What is the correct donor status?
A history of confirmed HIV, HCV or HBV infection leads to indefinite deferral, as the infection may persist and be transmitted by transfusion.
Forward typing shows no agglutination with either anti-A or anti-B reagent. The ABO group is:
Absence of both A and B antigens on red cells defines group O; AB cells would react with both reagents.
Anti-human globulin (Coombs) reagent is needed mainly to detect:
IgG ('incomplete') antibodies sensitise red cells but are too small to bridge them; AHG cross-links the bound IgG to produce visible agglutination.
Which of these tests is a mandatory screen on every donated unit?
Syphilis screening is compulsory for all donations. CMV is tested only for selected recipients, hepatitis A is not routinely screened, and malaria testing depends on local epidemiology.
When an antibody binds red cells and activates complement to completion, the cells rupture and release haemoglobin. This reaction end-point is called:
Formation of the membrane attack complex lyses red cells, which is read as haemolysis and is a positive reaction. Sensitisation is only antibody coating.
Anti-A and anti-B found in people never exposed to foreign red cells are described as:
ABO antibodies arise without red-cell exposure, probably from environmental antigens resembling A and B; they are mainly IgM. Immune antibodies need transfusion or pregnancy.