Anemia Types: Iron Deficiency vs B12/Folate vs Sickle Cell — MCV, Smear, Treatment
The NCLEX gives you a hemoglobin of 9 and expects you to know which anemia it is. Picking iron supplements for a B12 deficiency wastes time while irreversible nerve damage progresses. MCV direction, smear findings, and one key lab narrow it to the correct type — and the correct intervention.
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Comparison
- ↓ iron stores then ↓ Hgb synthesis
- Chronic blood loss (GI, menses), pregnancy
- ↓ B12
- pernicious anemia (no intrinsic factor)
- Gastrectomy, vegan diet, ileal resection
- ↓ folate intake/absorption
- Alcoholism, pregnancy, methotrexate/phenytoin
- Autosomal recessive Hgb SS
- RBCs sickle under hypoxia/dehydration
- Pica + koilonychia (spoon nails)
- Paresthesias, ataxia, memory loss
- Smooth beefy-red tongue
- ★NO neuro symptoms (vs B12)
- ★Vaso-occlusive pain crises
- Jaundice, splenomegaly
- ↓ MCV (microcytic < 80)
- ↓ ferritin (most specific), ↑ TIBC
- ↑ MCV (macrocytic > 100)
- ★↓ B12, ↑ methylmalonic acid
- ↑ MCV (macrocytic > 100)
- ↓ folate, ↑ homocysteine, normal MMA
- Normal MCV
- sickle cells on smear
- ★Hgb electrophoresis: ↑ Hgb S
- Give oral iron w/ vit C, empty stomach
- Find/treat blood-loss source
- Protect from injury (ataxia)
- Lifelong IM B12 if pernicious
- Replace folate
- correct cause
- Crisis: hydration, O₂, pain control
- Avoid triggers
- monitor for sequestration
- Oral ferrous sulfate
- IV iron if severe
- IM cyanocobalamin (lifelong if PA)
- Oral B12 if dietary cause
- Folic acid 1 mg/day PO
- Hydroxyurea ↑ Hgb F
- Crisis: IV fluids, O₂, opioids
- transfusion
- Stools turn black/tarry (expected)
- Avoid antacids/dairy within 2 hr of dose
- Lifelong injections if IF absent
- Report numbness/tingling early
- Take folate before & during pregnancy
- Limit alcohol
- eat leafy greens
- Avoid dehydration, hypoxia, cold, altitude
- Hydrate aggressively
- genetic counseling
- Severe anemia then high-output failure
- Subacute combined degeneration (irreversible)
- Pregnancy: fetal neural tube defects
- Acute chest syndrome
- splenic sequestration
- Stroke, priapism
- Chronic fatigue
- cardiac strain
- Permanent neurologic deficits
- Fetal NTDs
- chronic anemia
- Organ infarction
- chronic pain
- early death
Iron Deficiency
- ↓ iron stores then ↓ Hgb synthesis
- Chronic blood loss (GI, menses), pregnancy
B12 Deficiency
- ↓ B12
- pernicious anemia (no intrinsic factor)
- Gastrectomy, vegan diet, ileal resection
Iron Deficiency
- Pica + koilonychia (spoon nails)
B12 Deficiency
- Paresthesias, ataxia, memory loss
- Smooth beefy-red tongue
Iron Deficiency
- ↓ MCV (microcytic < 80)
- ↓ ferritin (most specific), ↑ TIBC
B12 Deficiency
- ↑ MCV (macrocytic > 100)
- ★↓ B12, ↑ methylmalonic acid
Iron Deficiency
- Give oral iron w/ vit C, empty stomach
- Find/treat blood-loss source
B12 Deficiency
- Protect from injury (ataxia)
- Lifelong IM B12 if pernicious
Iron Deficiency
- Oral ferrous sulfate
- IV iron if severe
B12 Deficiency
- IM cyanocobalamin (lifelong if PA)
- Oral B12 if dietary cause
Iron Deficiency
- Stools turn black/tarry (expected)
- Avoid antacids/dairy within 2 hr of dose
B12 Deficiency
- Lifelong injections if IF absent
- Report numbness/tingling early
Iron Deficiency
- Severe anemia then high-output failure
B12 Deficiency
- Subacute combined degeneration (irreversible)
Iron Deficiency
- Chronic fatigue
- cardiac strain
B12 Deficiency
- Permanent neurologic deficits
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Low MCV → check ferritin (iron). High MCV → check B12 vs folate. Normal MCV + crises → sickle cell.
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