Hypercalcemia in Lung Cancer due to Simultaneously Elevated PTHrP and Ectopic Calcitriol Production: First Case Report

Calcitriol-mediated hypercalcemia has been reported in malignant lymphomas and granulomatous diseases but not in lung carcinoma. We describe a patient with squamous cell lung carcinoma with hypercalcemia and elevated calcitriol levels. A 60-year-old Caucasian male patient with stage IIIB squamous cell lung cancer developed hypercalcemia at 14.8 mg/dL two years after receiving chemotherapy and radiotherapy where labs showed a serum intact PTH: 7 pg/mL, PTHrP: 30 pmol/L, 1,25-hydroxyvitamin D (calcitriol): 76 pg/mL, and 25-hydroxyvitamin D levels: