Fulminating hypercalcemia and markedly increased nephrogenous cyclic AMP in a patient with transitional cell carcinoma of the bladder

Refractory hypercalcemia developed suddenly in a patient who had undergone a radical cystectomy for an anaplastic transitional cell carcinoma of the bladder. A normal serum parathyroid hormone (PTH) value was obtained by immunoassay while the patient had hypercalcemia and unimpaired renal function. This normal PTH value in the presence of hypercalcemia was consistent with his hypercalcemia being secondary to excessive amounts of circulating PTH. The finding of increased nephrogenous cyclic AMP, however, provided the definitive diagnosis of hyperparathyroidism. Since autopsy revealed that there was no residual tumor in the bladder area, only evidence of metastatic disease, and since the parathyroid glands were not hyperplastic or adenomatous, we attributed this patient's hypercalcemia to hyperparathyroidism due to the ectopic production of PTH by a metastasis from the transitional cell carcinoma of the bladder.