Refractory hypercalcemia due to iatrogenic unintentional Vitamin D intoxication unmasked by pancreatitis: Lessons learnt from an atypical case.

We present the case of a 64-year-old Caucasian man with severe abdominal pain and vomiting preceded by recurrent epigastric pain, nausea, polyuria, polydipsia, constipation, and weight loss. The patient had significantly elevated calcium 3.84 mmol/L (2.20-2.60), advanced renal impairment with serum creatinine 253 μmol/L (59-104), serum urea 11.2 mmol/L(2.5-7.8), elevated serum lipase 1599 U/L (13-60). Hematological studies revealed normocytic normochromic anemia, Hb 96 g/L(130-170), adequately suppressed parathyroid hormone 1.3 pmol/L (1.8-7.9), indicating parathyroid independent hypercalcemia. Abdominal computed tomography (CT) imaging showed features of acute pancreatitis and several non-obstructing left renal calculi. The patient was treated in hospital with intravenous fluid therapy, intravenous PPI therapy, and analgesics. Vitamin D supplements were discontinued. He also received intravenous pamidronate infusion during his hospital stay. The patient required another hospitalization three months after discharge for intravenous fluid therapy due to worsening hypercalcemia and required a second dose of intravenous pamidronate therapy. Seven months after the initial presentation, the patient's serum calcium levels remained within normal limits without the need for medical treatment. His 25-hydroxyvitamin D level became detectable and reached 285 nmol/L after 16 months. His renal function also improved significantly: the estimated glomerular filtration rate (eGFR) was 51 mL/min after 16 months, compared with 21 mL/min at the initial presentation. The patient was discharged and returned to the care of his primary care physician.