A 52-year-old vegetarian woman from rural India presents with progressive fatigue, glossitis, and paresthesias in both feet. Blood smear shows macrocytic RBCs with hypersegmented neutrophils. Serum B12 is 180 pg/mL (normal 200) and folate is normal. What is the drug of choice for her anemia?

Question

A 52-year-old vegetarian woman from rural India presents with progressive fatigue, glossitis, and paresthesias in both feet. Blood smear shows macrocytic RBCs with hypersegmented neutrophils. Serum B12 is 180 pg/mL (normal >200) and folate is normal. What is the drug of choice for her anemia?

Accepted Answer

B. Cyanocobalamin 1000 mcg intramuscularly monthly. ## Diagnosis: Vitamin B12 Deficiency Megaloblastic Anemia

This patient has classic B12 deficiency with neurological manifestations (paresthesias, glossitis) and megaloblastic morphology. The serum B12 level of 180 pg/mL confirms deficiency.

## First-Line Treatment: Cyanocobalamin

**Key Point:** Cyanocobalamin (not hydroxocobalamin) is the standard first-line agent for B12 deficiency in India and most countries. It is the most commonly used form and is cost-effective.

**High-Yield:** Standard dosing is 1000 mcg intramuscularly:
- Weekly for 6 weeks (loading phase) if neurological symptoms present, OR
- Monthly maintenance once B12 stores are replete

In this case, given the presence of neurological signs (paresthesias), weekly dosing for 6 weeks followed by monthly maintenance is appropriate.

## Why Cyanocobalamin Over Hydroxocobalamin?

| Feature | Cyanocobalamin | Hydroxocobalamin |
|---------|---|---|
| **First-line in India** | Yes | No |
| **Cost** | Lower | Higher |
| **Efficacy** | Excellent | Excellent |
| **Frequency** | Monthly maintenance standard | Weekly × 6 then monthly (more intensive) |
| **Use case** | All B12 deficiency | Preferred in some Western countries for neurological disease |

**Clinical Pearl:** Hydroxocobalamin is NOT superior in efficacy and is not routinely used in Indian practice. Cyanocobalamin is the standard of care.

**Mnemonic:** **CYANO = Standard** — Cyanocobalamin is the standard first-line B12 replacement globally and in India.

Answer

A. Hydroxocobalamin 1000 mcg intramuscularly weekly for 6 weeks then monthly

Answer

C. Folic acid 5 mg orally daily

Answer

D. Pyridoxine 50 mg orally daily

A 52-year-old vegetarian woman from rural India presents with progressive fatigue, glossitis, and paresthesias in both feet. Blood smear shows macrocytic RBCs with hypersegmented neutrophils. Serum B12 is 180 pg/mL (normal >200) and folate is normal. What is the drug of choice for her anemia?

Explanation

Diagnosis: Vitamin B12 Deficiency Megaloblastic Anemia

First-Line Treatment: Cyanocobalamin

Why Cyanocobalamin Over Hydroxocobalamin?

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Feature	Cyanocobalamin	Hydroxocobalamin
First-line in India	Yes	No
Cost	Lower	Higher
Efficacy	Excellent	Excellent
Frequency	Monthly maintenance standard	Weekly × 6 then monthly (more intensive)
Use case	All B12 deficiency	Preferred in some Western countries for neurological disease