MLT Exam
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MLT Exam is a trademark of its owner, which is not affiliated with and does not endorse Test Treasure Publication or TTP Prep.
10 sample questions for the MLT Exam, with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.
Sections covered on the exam: Blood Banking - Blood Groups, Antibodies and Compatibility Testing, Blood Banking - Donors, Components and Transfusion Practice, Hematology - Leukocyte and Platelet Disorders and Hemostasis, Clinical Chemistry - Carbohydrates, Lipids, Proteins, Enzymes, Liver and Kidney, Clinical Chemistry - Electrolytes, Acid-Base, Endocrinology, TDM and Toxicology, Hematology - Cell Counts, Morphology and Red Cell Disorders, Immunology and Serology, Microbiology - Susceptibility, Mycobacteria, Mycology, Parasitology and Virology, Laboratory Operations - Quality, Safety, Lab Math and Instrumentation.
Question 1 · Blood Banking - Blood Groups, Antibodies and Compatibility Testing
A pretransfusion antibody screen is positive at the antiglobulin (AHG) phase only, with no reactivity at immediate spin or 37 C. A panel was tested; the following table lists the relevant antigens and the AHG reaction of each cell. The autocontrol is negative. M, N, S, s, P1, Lea and Leb were excluded on other nonreactive panel cells that are not shown.
| Cell | Rh and Kell | Duffy | Kidd | AHG reaction |
|---|---|---|---|---|
| 1 | rr (c, e), K- | Fy(a-b+) | Jk(a+b-) | 2+ |
| 2 | R2R2 (D, c, E), K+ | Fy(a+b-) | Jk(a-b+) | 0 |
| 3 | rr (c, e), K- | Fy(a-b+) | Jk(a-b+) | 0 |
| 4 | R1R1 (D, C, e), K- | Fy(a+b+) | Jk(a-b+) | 0 |
| 5 | R1R1 (D, C, e), K- | Fy(a+b-) | Jk(a+b+) | 1+ |
| 6 | R2R2 (D, c, E), K- | Fy(a+b+) | Jk(a+b-) | 2+ |
Answer: D. Anti-Jka
Only the three Jk(a+) cells react, and the homozygous Jk(a+b-) cells react more strongly than the heterozygous Jk(a+b+) cell, the dosage pattern typical of Kidd antibodies. Anti-Fyb is excluded by nonreactive Fy(a-b+) cell 3, anti-c by homozygous c cells 2 and 3, and anti-E by homozygous E cell 2; three positive and three negative cells satisfy the rule of three.
Question 2 · Hematology - Leukocyte and Platelet Disorders and Hemostasis
Answer: B. Cyanide-nitroprusside test
Hexagonal plates in acid urine suggest cystine, an abnormal crystal of cystinuria, which is confirmed by the cyanide-nitroprusside test. Ammonium sulfate separates hemoglobin from myoglobin, Watson-Schwartz detects porphobilinogen, and SSA precipitates protein.
Question 3 · Clinical Chemistry - Electrolytes, Acid-Base, Endocrinology, TDM and Toxicology
Answer: C. 8.8 mg/dL
Applying the correction, corrected Ca = 7.6 + 0.8 x (4.0 - 2.5) = 7.6 + 1.2 = 8.8 mg/dL, inside the reference interval, so the low total calcium mainly reflects low albumin; ionized calcium is the definitive test. Leaving out the 0.8 factor gives 9.1, subtracting the correction gives 6.4, and multiplying 0.8 by the albumin itself gives 9.6.
Question 4 · Hematology - Leukocyte and Platelet Disorders and Hemostasis
A young adult with lifelong mucosal bleeding has a platelet count of 85 x 10^3/uL, and the smear shows many giant platelets. Light transmission aggregometry gives the following results.
| Agonist | Aggregation |
|---|---|
| ADP | Normal |
| Collagen | Normal |
| Epinephrine | Normal |
| Arachidonic acid | Normal |
| Ristocetin | Absent; not corrected by adding normal plasma |
Answer: A. Bernard-Soulier syndrome
Absent ristocetin aggregation that normal plasma cannot correct, with thrombocytopenia and giant platelets, indicates a missing GP Ib/IX receptor (Bernard-Soulier syndrome). Von Willebrand disease is corrected by normal plasma because the plasma supplies VWF, Glanzmann thrombasthenia fails with every agonist except ristocetin, and aspirin abolishes arachidonic acid aggregation.
Question 5 · Blood Banking - Blood Groups, Antibodies and Compatibility Testing
Answer: B. Staphylococcus saprophyticus
Coagulase-negative staphylococci are split by novobiocin: S. saprophyticus is resistant and is a classic cause of urinary tract infection in young women. S. epidermidis is coagulase negative but novobiocin susceptible, and S. aureus is coagulase positive.
Question 6 · Blood Banking - Blood Groups, Antibodies and Compatibility Testing
A 61-year-old woman with no transfusion history but three prior pregnancies has a positive antibody screen. An 11-cell panel is tested. The following table summarizes the panel by test phase. Her DAT is negative, and the reactions are the same strength with homozygous and heterozygous cells for every common antigen.
| Phase | Panel cells 1-11 | Autocontrol |
|---|---|---|
| Immediate spin | 0 | 0 |
| 37 C (LISS) | 0 | 0 |
| AHG | 2+ with every cell | 0 |
| Check cells | Not needed (all tubes positive) | Agglutinated |
Answer: C. An alloantibody to a high-prevalence antigen
Uniform AHG reactivity with all panel cells, a negative autocontrol and a negative DAT point to an alloantibody against an antigen present on nearly all cells; the next steps are antigen-negative selected cells, phenotyping and a search for compatible donors (including siblings or rare donor programs). A warm autoantibody would make the autocontrol and DAT positive, multiple antibodies usually vary in strength, and rouleaux appears at immediate spin.
Question 7 · Hematology - Leukocyte and Platelet Disorders and Hemostasis
Answer: C. Galactose
Copper reduction detects any reducing sugar, while glucose oxidase is specific for glucose; a positive Clinitest with a negative strip in an infant suggests galactose, as in galactosemia. Glucose would make both tests positive.
Question 8 · Clinical Chemistry - Electrolytes, Acid-Base, Endocrinology, TDM and Toxicology
A thin woman with fatigue, low blood pressure and darkening of her skin has the following morning results, including a cosyntropin (ACTH) stimulation test.
| Test | Result | Reference interval |
|---|---|---|
| Sodium | 128 mEq/L | 136-145 |
| Potassium | 5.9 mEq/L | 3.5-5.1 |
| Glucose | 62 mg/dL | 70-99 |
| Cortisol, 8 a.m. | 2.1 mcg/dL | 5-23 |
| ACTH | 410 pg/mL | 10-60 |
| Cortisol 60 min after cosyntropin | 3.0 mcg/dL | 18 or more |
Answer: D. Primary adrenal insufficiency (Addison disease)
Low cortisol with a very high ACTH and no response to cosyntropin places the defect in the adrenal cortex, and loss of aldosterone explains the hyponatremia and hyperkalemia. Pituitary failure would give a low ACTH and usually normal potassium, and SIADH does not raise potassium or lower cortisol.
Question 9 · Hematology - Leukocyte and Platelet Disorders and Hemostasis
A 16-year-old girl has heavy menstrual periods and frequent nosebleeds, and her mother has a similar history. The following results are obtained.
| Test | Result | Reference interval |
|---|---|---|
| Platelet count | 260 x 10^3/uL | 150-450 |
| PT | 12.1 s | 11.0-13.5 |
| aPTT | 41 s | 25-35 |
| VWF antigen | 28% | 50-150 |
| VWF ristocetin cofactor activity | 25% | 50-150 |
| Factor VIII activity | 38% | 50-150 |
Answer: D. Von Willebrand disease
Proportionally low VWF antigen and activity with a mildly low factor VIII (which VWF normally protects), mucosal bleeding and an affected mother fit type 1 von Willebrand disease, the most common inherited bleeding disorder. Hemophilia A is X-linked with normal VWF, and the platelet disorders do not lower VWF or factor VIII.
Question 10 · Blood Banking - Blood Groups, Antibodies and Compatibility Testing
Answer: C. Neisseria meningitidis
N. meningitidis oxidizes glucose and maltose only. N. gonorrhoeae uses glucose alone, N. lactamica also uses lactose (ONPG positive), and Moraxella catarrhalis produces acid from none of these sugars.
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