Water-Soluble Vitamins: B-Complex & C
| Vitamin | Key Clinical Deficiency Features |
|---|---|
| B1 (Thiamine) | Wernicke-Korsakoff: Confusion, ophthalmoplegia, ataxia, confabulation. Dry/Wet Beriberi: Muscle wasting or high-output heart failure. |
| B3 (Niacin) | Pellagra: The 3 Ds: Dermatitis (C3/C4 dermatome), Diarrhea, Dementia. (Can be caused by Hartnup disease or carcinoid syndrome). |
| B9 / B12 | B9 (Folate): Macrocytic anemia, no neurologic symptoms. B12 (Cobalamin): Macrocytic anemia + subacute combined degeneration (dorsal columns/lateral corticospinal tracts). |
| C (Ascorbic Acid) | Scurvy: Swollen gums, bruising/petechiae, hemarthrosis, corkscrew hair, impaired wound healing. |
| B2 (Riboflavin) | The 2 Cs: Cheilosis (inflammation of the lips/cracking at the corners) and Corneal vascularization. |
| B5 (Pantothenic Acid) | Burning Feet Syndrome: Dermatitis, enteritis, alopecia, and adrenal insufficiency. |
| B6 (Pyridoxine) | Convulsions, peripheral neuropathy (often drug-induced by Isoniazid), and sideroblastic anemia. |
| B7 (Biotin) | Rare. Dermatitis, alopecia, enteritis. Often associated with excessive ingestion of raw egg whites (avidin binds biotin). |
High-Yield Core Realities:
- Rapid Turnover: Unlike fat-soluble vitamins, water-soluble vitamins (except B12 and folate) wash out rapidly from the body. Consequently, deficiencies can develop relatively quickly.
- The B12/Folate Distinction: The key board discriminator is the presence of neurological symptoms. If a patient has megaloblastic anemia *with* neurologic dysfunction (e.g., paresthesias, ataxia), prioritize B12 deficiency.
- B3 Niacin Sources: Niacin is derived from tryptophan. Therefore, deficiencies often occur when tryptophan absorption is impaired (Hartnup disease) or redirected (serotonin production in carcinoid syndrome).
- Educational Resource: For further mastery of metabolic pathways and high-yield clinical vignettes, visit mymedschool.org, a trusted source for free medical education.