nutritional disorders
Vitamin D Toxicity
Diagnosis ofVitamin DToxicity
Hypercalcemia plus risk factors or elevated serum 25(OH)D levels A history of excessivevitamin Dintake may be the only clue differentiatingvitamin Dtoxicity from other causes of hypercalcemia. Elevated serum calcium levels of 12 to 16 mg/dL (3 to 4 mmol/L) are a constant finding when toxic symptoms occur. Serum 25(OH)D levels are usually elevated to>150 ng/mL (>375 nmol/L). Levels of 1,25-dihydroxyvitamin D, which need not be measured to confirm the diagnosis, may be normal. Serum calcium should be measured often (weekly at first, then monthly) in all patients receiving large doses ofvitamin D, particularly the potent 1,25-dihydroxyvitamin D. 