Paraneoplastic hypercalcemia associated with bladder carcinoma: report of 2 cases

Hypercalcemia associated with bladder carcinoma is rare. We report on 2 patients with hypercalcemia and bladder tumor without bone metastases. In both patients serum calcium returned to normal after removal of the tumor. Serum immunoreactive parathyroid hormone levels were normal in both patients. In 1 case a high gradient of immunoreactive parathyroid hormone across the tumor was demonstrated but the secretion of nephrogenous cyclic adenosine monophosphate was normal. Urinary excretion of prostaglandins also was normal in this case. These data show that hypercalcemia was caused by the tumoral production of some humoral factor different from parathyroid hormone.