Vitamin D Toxicity: A Prospective Study from a Tertiary Care Centre in Kashmir Valley.

Vitamin D toxicity (VDT), a "not uncommon" cause of hypercalcemia, can be life-threatening and cause substantial morbidity, if not treated promptly.To describe presentation, management, and outcome in 32 patients with VDT diagnosed over 3 years.Patients presenting with VDT at a tertiary care centre in Srinagar Kashmir India were included. Evaluation included detailed history and biochemical tests including serum calcium, phosphate, creatinine, intact parathyroid hormone (iPTH), 25-hydroxy Vitamin D (25-OHD), and 24-hour urinary calcium.

The clinical manifestations of the 32 patients (median age 65; range 3-77 years) included gastrointestinal symptoms (constipation and vomiting), polyuria/polydipsia, altered sensorium, pancreatitis, acute kidney injury, and nephrocalcinosis. The median total serum calcium level was 13.95 (range 11.10-17.20) mg/dl and median 25-OHD level was 306 (range 105-2800) ng/ml. All patients had suppressed or low normal iPTH and hypercalciuria and 78% had azotemia. All patients had received multiple intramuscular injections of vitamin D₃. The median cumulative dose was 4,200,000 (range, 1,800,000-30,000,000) IU. The median time to resolution of hypercalcemia was 7 months (range 4-18 months).

We conclude that VDT is an increasingly common cause of symptomatic hypercalcemia. VDT needs prolonged follow up as it takes months to abate its toxicity. Enhancing awareness among general practitioners regarding the toxicity resulting from high doses of vitamin D is the key to prevent VDT. We suggest that VDT be considered in patients, especially the elderly, presenting with polyuria, polydispsia, vomiting, azotemia, or encephalopathy.