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PA14.1-2 | Microcytic Anemias — Graded Quiz
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A 32-year-old woman with heavy menstrual bleeding for 3 years develops progressive fatigue. Labs: Hb 8.1 g/dL, MCV 65 fL, serum ferritin 4 ng/mL, TIBC 510 µg/dL, transferrin saturation 6%. She has CRP of 62 mg/L from a current urinary tract infection. Her colleague suggests checking a soluble transferrin receptor (sTfR) level. Which explanation BEST justifies the sTfR request over relying on ferritin alone?
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A 25-year-old Gujarati man is referred for pre-marital screening. His CBC: Hb 12.2 g/dL, MCV 61 fL, RBC 6.1 × 10¹²/L. Mentzer Index = 61 ÷ 6.1 = 10.0. Ferritin = 55 ng/mL (normal). HPLC: HbA₂ = 4.9% (elevated). His fiancée's HPLC shows HbA₂ = 5.3%. Which counselling statement is MOST accurate for this couple?
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A 50-year-old man with tuberculosis on 6 months of anti-tuberculosis therapy (ATT) including isoniazid develops progressive weakness. CBC: Hb 9.4 g/dL, MCV 70 fL, RDW 21% (elevated). Peripheral smear: two distinct populations of red cells — one normocytic normochromic, another microcytic hypochromic. Serum ferritin 550 ng/mL (very elevated). Transferrin saturation 72% (very elevated). What is the MOST likely diagnosis and mechanism?
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A 65-year-old woman with CKD Stage 4 (GFR 22 mL/min) and rheumatoid arthritis has: Hb 9.1 g/dL, MCV 77 fL, serum iron 30 µg/dL, TIBC 145 µg/dL, ferritin 380 ng/mL, hepcidin 95 ng/mL (markedly elevated, normal <20). Her nephrologist plans EPO therapy. Which mechanism, mediated by hepcidin, will LIMIT the response to EPO in this patient?
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A peripheral blood smear from a patient with Hb 7.8 g/dL and MCV 60 fL shows the following: markedly microcytic hypochromic cells, prominent pencil-shaped (elliptical) red cells with central pallor >1/3 diameter, occasional target cells, anisocytosis, and a few fragmented cells. The RBC count is 3.1 × 10¹²/L (low for the degree of microcytosis). Mentzer Index = 60 ÷ 3.1 = 19.4. Which diagnosis does this smear pattern MOST support?
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A 28-year-old woman with a known diagnosis of beta-thalassaemia trait (HbA₂ 5.1%) develops progressive fatigue during her second trimester of pregnancy. CBC: Hb 9.8 g/dL, MCV 63 fL, ferritin 6 ng/mL (low). Her obstetrician prescribes oral iron. After 8 weeks, the haemoglobin rises to 11.2 g/dL. Which SINGLE laboratory test is now MOST important before discharge from the antenatal clinic at this visit?
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A peripheral blood smear from a 45-year-old man with MCV 74 fL and Hb 10.2 g/dL shows: numerous target cells, mild hypochromia, some microcytes, occasional polychromasia. His ferritin is 68 ng/mL (normal), iron studies normal. HPLC: HbA₂ 2.8% (normal), HbA 92.1%, HbF 0.4%. His father died of 'blood disease' at age 40. Which smear finding MOST helps distinguish ACD from the leading alternative diagnosis in this patient?
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A 22-year-old Sindhi woman presents to a haematology clinic for pre-marital counselling. Her CBC: Hb 11.9 g/dL, MCV 64 fL, RBC 5.8 × 10¹²/L. Serum ferritin = 42 ng/mL (normal). HPLC: HbA₂ 3.0% (normal upper limit 3.5%), HbA 97%, HbF 0.2%. Her fiancé has HbA₂ 5.2%. The haematologist is uncertain whether she has beta-thalassaemia trait or alpha-thalassaemia. Which additional investigation is MOST helpful?
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During a pathology practical, a student reviews four peripheral smears from patients with microcytic anaemia. Smear 3 is from a 55-year-old man with a 2-year history of joint pain and morning stiffness (confirmed RA). His CBC: Hb 10.4 g/dL, MCV 76 fL, serum iron 30 µg/dL, TIBC 160 µg/dL (low), ferritin 285 ng/mL, transferrin saturation 18.75%. The peripheral smear shows: mild hypochromia, mild microcytosis, few target cells, no pencil cells, no stippling, no dimorphic population. Which is the MOST diagnostically useful smear feature that DIFFERENTIATES this from IDA?
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A 40-year-old man with a history of alcohol use disorder is found to have Hb 10.8 g/dL, MCV 72 fL. Serum ferritin is 920 ng/mL (markedly elevated), transferrin saturation is 68% (elevated). Peripheral smear shows a DIMORPHIC red cell population — one normocytic normochromic, another microcytic hypochromic — with coarse basophilic stippling. Bone marrow Prussian blue stain shows ringed sideroblasts (>15% of erythroblasts). What is the MOST specific smear feature that distinguishes this from thalassaemia trait?
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A 38-year-old battery recycling worker presents with colicky abdominal pain, constipation, and progressive weakness for 4 months. CBC: Hb 10.2 g/dL, MCV 74 fL, RDW 18.5%. Peripheral smear reveals two RBC populations plus prominent coarse basophilic stippling in >30% of erythrocytes. Serum ferritin is 520 ng/mL, transferrin saturation 58%. Blood lead level (BLL) is 72 µg/dL (severe toxicity threshold >45 µg/dL). Which enzyme does lead inhibit at TWO steps in the haem synthesis pathway, producing the characteristic smear findings?
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A 30-year-old woman presents with fatigue. CBC: Hb 9.4 g/dL, MCV 68 fL. Peripheral smear: numerous target cells (bulls-eye pattern), mild-to-moderate hypochromia, microcytes, occasional basophilic stippling. RBC count 5.2 × 10¹²/L (Mentzer Index = 68 ÷ 5.2 = 13.1). Ferritin = 48 ng/mL (normal). HPLC: HbA₂ = 5.0%, HbF = 3.2%, HbA = 91.8%. The MOST characteristic smear feature of this condition that also distinguishes it from IDA is:
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