Haemoglobin, red cell indices and anaemias

35 Kerala MSc MLT Entrance practice questions on Haemoglobin, red cell indices and anaemias, part of Haematology and Blood Banking. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Medium

   A sample shows a band in the HbS position at pH 8.6, a negative sickling solubility test, and a single band with HbA on acid citrate agar. The variant is most likely:

   1. AHbS trait
   2. BHbE
   3. CHbC
   4. DHbD Punjab

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   Answer: D · HbD Punjab

   At pH 8.4-8.6, HbD Punjab (and HbG) carries the same charge as HbS and moves to the same position, so a band in the S position is not proof of HbS. The two are separated by the solubility test, which is negative for HbD, and by acid citrate agar electrophoresis at pH 6.0-6.2, where HbD runs with HbA. HPLC also separates them by retention time. HbD Punjab is found mainly in Punjab and neighbouring regions, while HbE is common in north-east India.

   • A: HbS gives a positive solubility test and separates from HbA on acid agar.
   • B: HbE runs with HbA2 and HbC at alkaline pH, not with HbS.
   • C: HbC runs with HbA2 at alkaline pH and separately from HbA on acid agar.

2. Question 2 · Easy

   For the Westergren ESR, blood is mixed with trisodium citrate anticoagulant in the proportion of:

   1. A4 volumes of blood to 1 of citrate
   2. B1 volume of blood to 4 of citrate
   3. C9 volumes of blood to 1 of citrate
   4. D1 volume of blood to 1 of citrate

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   Answer: A · 4 volumes of blood to 1 of citrate

   The Westergren method uses 4 parts blood to 1 part trisodium citrate, which both anticoagulates and dilutes the sample, and the 200 mm tube is read at exactly 1 hour. Coagulation tests use a 9:1 ratio instead, so the two tubes are not interchangeable. The tube must stand vertical, at room temperature, away from vibration and direct sunlight. Tilting the tube or warming it speeds sedimentation and gives a falsely high ESR.

   • B: Inverting the ratio would leave the sample mostly anticoagulant.
   • C: A 9:1 ratio is used for coagulation tests, not for the ESR.
   • D: Equal volumes would over-dilute the sample and invalidate the reference range.

3. Question 3 · Medium

   Which iron profile points to iron deficiency anaemia rather than anaemia of chronic disease?

   1. AHigh ferritin, low TIBC
   2. BLow serum iron, low saturation
   3. CLow ferritin, high TIBC
   4. DNormal ferritin, low TIBC

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   Answer: C · Low ferritin, high TIBC

   In iron deficiency the stores are empty, so ferritin falls, and the liver makes more transferrin, so TIBC rises. In anaemia of chronic disease, hepcidin traps iron in macrophages: serum iron is low, but ferritin is normal or raised and TIBC is low or normal. Low serum iron and low transferrin saturation occur in both, so they do not separate the two. Ferritin is an acute-phase protein, so a normal ferritin during inflammation can still hide iron deficiency.

   • A: High ferritin with low TIBC is the pattern of anaemia of chronic disease.
   • B: Low serum iron and saturation occur in both conditions and do not separate them.
   • D: Normal ferritin with low TIBC also fits anaemia of chronic disease.

4. Question 4 · Hard

   Ten days after acute haemolysis that followed a meal of fava beans, a 30-year-old man has reticulocytes of 12%, a negative DAT, and a normal fluorescent spot test for G6PD. Bite cells were seen at presentation. How should the normal G6PD result be interpreted?

   1. AThe haemolysis must have been immune
   2. BHereditary spherocytosis is now likely
   3. CPossibly false, as young cells have more enzyme
   4. DG6PD deficiency is reliably excluded

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   Answer: C · Possibly false, as young cells have more enzyme

   In G6PD deficiency the oldest red cells have the least enzyme and are destroyed first in an oxidant crisis. The surviving cells and the new reticulocytes have much higher activity, so a screening test taken during or just after haemolysis can be falsely normal, especially with milder variants. Bite and blister cells, and Heinz bodies on a supravital stain, support oxidant haemolysis. The test should be repeated about 2-3 months after the episode, or a quantitative assay read against the reticulocyte count.

   • A: A negative DAT and the fava-bean trigger argue against immune haemolysis.
   • B: Bite cells after fava beans point to oxidant injury, not a membrane defect.
   • D: A test taken during the reticulocyte response cannot exclude the deficiency.

5. Question 5 · Medium

   The tube solubility test for HbS turns turbid because deoxygenated HbS:

   1. APrecipitates when heated in isopropanol
   2. BIs insoluble in concentrated phosphate buffer
   3. CMigrates slowly at alkaline pH
   4. DResists denaturation by strong alkali

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   Answer: B · Is insoluble in concentrated phosphate buffer

   The reagent contains sodium dithionite to deoxygenate haemoglobin, saponin to lyse the cells, and a high-molarity phosphate buffer. Deoxy-HbS polymerises and is insoluble in this buffer, so the tube becomes turbid, while HbA stays in clear solution. The test does not separate sickle cell trait from sickle cell disease, so a positive result needs electrophoresis or HPLC. False negatives occur in young infants with high HbF and in severe anaemia.

   • A: Precipitation in isopropanol or on heating detects unstable haemoglobins.
   • C: Electrophoretic mobility is the basis of electrophoresis, not of the solubility test.
   • D: Resistance to alkali denaturation is the property of HbF.

6. Question 6 · Easy

   Which haemoglobin derivative escapes conversion to cyanmethaemoglobin by Drabkin's reagent and so is missed by the method?

   1. ASulphaemoglobin
   2. BOxyhaemoglobin
   3. CCarboxyhaemoglobin
   4. DMethaemoglobin

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7. Question 7 · Hard

   A patient on parenteral nutrition with intravenous lipid has Hb 13.5 g/dL, RBC 3.7 million/µL, MCV 89 fL, MCH 36.5 pg and MCHC 41 g/dL (reference MCH 27-32 pg, MCHC 32-36 g/dL). The best way to obtain a valid haemoglobin is to:

   1. AWarm the sample to 37°C and re-run it
   2. BRecollect the sample in sodium citrate
   3. CDilute the sample 1 in 2 and multiply by 2
   4. DReplace the plasma with saline and re-run

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8. Question 8 · Medium

   Why is the osmotic fragility test also done on blood incubated at 37°C for 24 hours when hereditary spherocytosis is suspected?

   1. AIncubation lyses reticulocytes that mask the defect
   2. BIncubation exaggerates the fragility of spherocytes
   3. CIncubation restores ATP to the damaged red cells
   4. DIncubation removes antibodies coating the red cells

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9. Question 9 · Hard

   A 14-month-old child has pallor, hepatosplenomegaly and Hb 5.2 g/dL, MCV 58 fL, with target cells and many nucleated red cells. HPLC shows HbF 94%, HbA2 3.2% and no HbA. Both parents have MCV below 70 fL and HbA2 of 5%. The most likely diagnosis is:

   1. AHbE-beta thalassaemia
   2. BHbH disease
   3. CHereditary persistence of fetal haemoglobin
   4. DHomozygous beta zero thalassaemia (major)

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10. Question 10 · Easy

    Which reducing agent is used in the slide test for sickle cells?

    1. A2% sodium metabisulphite
    2. B0.85% sodium chloride
    3. C2% sodium citrate
    4. D3% hydrogen peroxide

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11. Question 11 · Easy

    Cyanmethaemoglobin is measured in a photometer at a wavelength of:

    1. A340 nm
    2. B620 nm
    3. C415 nm
    4. D540 nm

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12. Question 12 · Hard

    An 11-year-old boy from Wayanad has repeated painful crises. Hb is 7.5 g/dL, MCV 84 fL, and the film shows sickle and target cells. HPLC shows HbS 82%, HbF 15%, HbA2 2.8% and no HbA. Neither parent has a low MCV. The most likely diagnosis is:

    1. AHbSD disease
    2. BSickle cell-beta zero thalassaemia
    3. CSickle cell trait (HbAS)
    4. DSickle cell anaemia (HbSS)

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13. Question 13 · Easy

    Heinz bodies in red cells are best shown by:

    1. ASupravital crystal violet stain
    2. BPeriodic acid-Schiff stain
    3. CLeishman stain
    4. DPerls Prussian blue stain

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14. Question 14 · Easy

    Pencil cells (elongated elliptocytes) with microcytic hypochromic red cells are typical of:

    1. AAplastic anaemia
    2. BHereditary spherocytosis
    3. CMegaloblastic anaemia
    4. DIron deficiency anaemia

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15. Question 15 · Hard

    In the cyanmethaemoglobin method (dilution 1 in 251), a 60 mg/dL cyanmethaemoglobin standard reads 0.45 and a patient's diluted sample reads 0.36 at 540 nm. The haemoglobin is:

    1. A18.8 g/dL
    2. B12.0 g/dL
    3. C0.05 g/dL
    4. D1.2 g/dL

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16. Question 16 · Medium

    A sample with a WBC count of 1,20,000/µL gives a haemoglobin by the cyanmethaemoglobin method that is higher than expected. How should this be corrected?

    1. ALeave the sample in reagent for an hour before reading
    2. BCentrifuge the diluted sample and read the clear supernatant
    3. CRead the diluted sample at 415 nm instead of 540 nm
    4. DIncrease the dilution to 1 in 501 and double the result

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17. Question 17 · Medium

    In a patient with microcytic anaemia, a high red cell distribution width (RDW) favours:

    1. ABeta-thalassaemia trait
    2. BAlpha-thalassaemia trait
    3. CIron deficiency anaemia
    4. DHbE trait

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18. Question 18 · Hard

    A 30-year-old woman with SLE has Hb 7.9 g/dL, reticulocytes 11%, raised bilirubin and LDH, and many spherocytes. The DAT is positive with anti-IgG and weakly with anti-C3, and the eluate reacts with all panel cells at 37°C. The most likely diagnosis is:

    1. AWarm autoimmune haemolytic anaemia
    2. BG6PD deficiency haemolysis
    3. CHereditary spherocytosis
    4. DCold agglutinin disease

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19. Question 19 · Hard

    A 62-year-old man has tingling feet, a smooth red tongue, Hb 7.8 g/dL, MCV 118 fL, WBC 3,200/µL and platelets 90,000/µL. The film shows oval macrocytes and hypersegmented neutrophils. Serum B12 is low, and anti-intrinsic factor antibodies are positive. The most likely cause is:

    1. ADietary folate deficiency
    2. BAlcoholic liver disease
    3. CPernicious anaemia
    4. DMyelodysplastic syndrome

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20. Question 20 · Medium

    A Westergren tube is left tilted a few degrees from vertical during the hour. The ESR result will be:

    1. AFalsely high
    2. BNot affected
    3. CFalsely low
    4. DNot readable

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21. Question 21 · Medium

    Which condition is expected to give a low ESR?

    1. APlasma cell myeloma
    2. BSickle cell anaemia
    3. CPregnancy
    4. DIron deficiency anaemia

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22. Question 22 · Easy

    The mean cell volume (MCV) in fL is calculated as:

    1. AHb (g/dL) x 10 / RBC (millions/µL)
    2. BPCV (%) x 10 / RBC (millions/µL)
    3. CHb (g/dL) x 100 / PCV (%)
    4. DRBC (millions/µL) x 10 / PCV (%)

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23. Question 23 · Medium

    Coexisting iron deficiency can mask beta-thalassaemia trait because iron deficiency:

    1. ARaises the red cell count
    2. BShortens red cell survival
    3. CRaises the HbF level
    4. DLowers the HbA2 level

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24. Question 24 · Medium

    Decreased osmotic fragility (red cells more resistant to lysis) is seen in:

    1. ABurns
    2. BWarm autoimmune haemolysis
    3. CHereditary spherocytosis
    4. DThalassaemia

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25. Question 25 · Medium

    The current test of choice to diagnose paroxysmal nocturnal haemoglobinuria (PNH) is:

    1. AFlow cytometry for CD55 and CD59
    2. BHam's acidified serum test
    3. CSucrose lysis test
    4. DDirect antiglobulin test

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