MLT GlobeMOH exam preparation (UAE) – page 14
700 practice MCQs for the MOH medical laboratory exam. Level: Basic to intermediate.
What distinguishes Cushing 'disease' from other forms of Cushing syndrome?
'Cushing disease' is used only for pituitary ACTH-driven hypercortisolism. All other causes come under Cushing syndrome.
Besides its excretory role, the kidney makes which hormone that stimulates red cell production?
Peritubular interstitial cells release EPO in response to hypoxia. The kidney also makes renin and calcitriol. Thrombopoietin, angiotensinogen and hepcidin come mainly from the liver.
A patient's thyroid panel shows high free T4 caused by a hormone-secreting thyroid adenoma. What TSH result is expected?
Excess thyroid hormone from the gland itself (primary hyperthyroidism) exerts negative feedback on the pituitary, suppressing TSH. Raised TSH points to primary hypothyroidism or a TSH-secreting pituitary lesion.
Cryoprecipitate is the component of choice to replace:
Cryoprecipitate is made by thawing FFP at 1-6 °C. It is rich in fibrinogen, factor VIII, von Willebrand factor, factor XIII and fibronectin, and is used mainly for low fibrinogen.
Cellular blood components are irradiated to prevent:
Gamma or X-ray irradiation stops donor T lymphocytes from dividing, so they cannot attack the recipient. It is needed for immunocompromised patients, intrauterine transfusions and blood from relatives.
The direct antiglobulin test (DAT) detects:
The DAT tests the patient's own red cells with anti-IgG or anti-C3d to find in vivo coating, as in HDFN, transfusion reactions and autoimmune hemolysis. The indirect test (IAT) finds free antibody in plasma.
An encapsulated yeast seen with India ink in CSF of an HIV patient, which is urease positive, is:
Cryptococcus has a polysaccharide capsule that shows as a clear halo in India ink. Cryptococcal antigen testing of CSF or serum is more sensitive than India ink.
Red blood cell casts in urine sediment indicate:
Casts form in the tubules, so red cells inside a cast must come from the nephron. RBC casts point to glomerular disease such as post-streptococcal glomerulonephritis.
CSF with many neutrophils, high protein and glucose below 40% of the blood level suggests:
Bacteria and neutrophils consume glucose and damage the blood-brain barrier, raising protein. Viral meningitis shows lymphocytes with near-normal glucose.
A control has a mean of 200 mg/dL and an SD of 5 mg/dL. The coefficient of variation is:
CV = SD ÷ mean × 100 = 5 ÷ 200 × 100 = 2.5%. CV lets you compare the precision of methods at different concentrations.
Compared with adult red cells, ABO antigens on newborn red cells are:
A and B antigens are present at birth but weaker, as fewer branched chains are formed. Adult strength develops over the first few years of life.
Most routine anti-A and anti-B typing reagents used today are:
Current ABO reagents are mostly mouse monoclonal IgM antibodies, which are standardized and strong. Human polyclonal sera were used in the past; lectins serve special purposes.
The main purpose of washing red cells is to:
Saline washing removes about 99% of plasma proteins, useful for recurrent severe allergic reactions or IgA-deficient patients. It does not prevent GVHD.
In a stable adult without bleeding, one red cell unit is expected to raise the hemoglobin by about:
One unit usually raises hemoglobin by about 10 g/L (1 g/dL) and hematocrit by about 3% in an average adult.
A group B patient needs plasma. Which plasma groups are ABO-compatible?
Plasma must lack antibodies to the recipient's antigens. Group B plasma (anti-A) and AB plasma (no antibodies) are safe; group O plasma contains anti-B.
During donation, a donor becomes pale, sweaty and dizzy with a slow pulse. What is the correct first action?
These are signs of a vasovagal reaction. The needle is removed, the donor lies flat with legs raised, and cold compresses are applied; the collection is not continued.
The Kidd glycoprotein functions in the red cell membrane as a:
Kidd antigens are on the urea transporter (SLC14A1), which helps red cells keep osmotic stability in the renal medulla. The anion exchanger (band 3) carries the Diego antigens.
What is the normality of a 0.5 mol/L sulfuric acid (H2SO4) solution?
H2SO4 gives 2 replaceable H+ per molecule, so N = M × 2 = 0.5 × 2 = 1.0 N. Using 0.5 N ignores the valence of the acid.
A fasting glucose result is 90 mg/dL. Given a molecular weight of 180 g/mol, what is the result in SI units?
90 mg/dL = 900 mg/L; 900 ÷ 180 = 5.0 mmol/L (conversion factor 0.0555). 0.5 mmol/L forgets to convert dL to L.
When preparing a dilute solution from concentrated sulfuric acid, the correct technique is to:
Adding acid to water lets the large volume of water absorb the heat released. Adding water to acid can boil locally and splash concentrated acid.