Vitamin Toxicity: Clinical Recognition
| Vitamin | Toxicity Clinical Manifestations |
|---|---|
| Vitamin A | Acute: Nausea, vomiting, vertigo, blurred vision. Chronic: Alopecia, dry skin, hepatic toxicity (fibrosis/cirrhosis), pseudotumor cerebri (increased intracranial pressure), and teratogenicity (cleft palate, cardiac defects). |
| Vitamin D | Hypercalcemia, hypercalciuria, loss of appetite, stupor, and renal stones. Metastatic calcification of soft tissues (e.g., kidneys, blood vessels). |
| Vitamin E | Relatively rare. High doses may interfere with Vitamin K metabolism, increasing the risk of hemorrhagic stroke and bleeding complications, especially in patients on anticoagulants. |
| Vitamin B3 (Niacin) | Facial flushing (prevented by aspirin), hyperglycemia, and hyperuricemia (may precipitate gout). |
| Vitamin B6 | Sensory neuropathy (can occur with excessive supplementation). |
High-Yield Core Realities:
- Fat- vs. Water-Soluble: Toxicity is almost exclusively associated with fat-soluble vitamins (A, D, E, K) because they accumulate in the body. Water-soluble vitamin toxicity is uncommon due to renal excretion, with rare exceptions like B6 (neuropathy) and Niacin (flushing).
- Teratogenicity: Isotretinoin (a Vitamin A derivative) is a potent teratogen. It is strictly contraindicated in pregnancy; patients must have a negative pregnancy test before starting treatment.
- Clinical Management: Identification of toxicity is often based on detailed diet history and supplemental usage. Stopping the supplement is the primary therapeutic intervention.
- Educational Resource: For more detailed clinical cases, pharmacology correlations, and practice questions, visit mymedschool.org.