1985 Volume 76 Issue 4 Pages 308-314
In an attempt to analyze the pathological processes which lead to hypercalcemia in patients with multiple bone metastases, 23 advanced breast cancer patients with multiple bone metastases, three hypercalcemic patients with other malignancies and seven early breast cancer patients without any distant metastasis were studied. Of the 23 patients with advanced breast cancer, nine showed serum calcium levels higher than 10mg/dl. In five of the nine hypercalcemic patients with advanced breast cancer, urinary cyclic AMP excretion was lower than 4nmol/100ml of glomerular filtrate (GF), indicating that the secretion of parathyroid hormone was suppressed. However, urinary cyclic AMP excretion was higher than 4nmol/100ml of GF in the other four hypercalcemic patients with advanced breast cancer and three hypercalcemic patients with other malignancies. In patients with higher urinary cyclic AMP excretion, fractional excretion of calcium (FECa) showed a negative correlation (r=0.83, P<0.05) with urinary cyclic AMP. Parathyroid hormone immunoreactivity was not detected in any of six patients showing serum calcium levels higher than 11mg/dl. These results suggest that in about a half of hypercalcemic patients with advanced breast cancer and multiple bone metastasis, there is a factor which increases urinary cyclic AMP and enhances calcium reabsorption in the kidney, but which is different from parathyroid hormone. This factor may facilitate retention of calcium mobilized into the circulation by bone metastases, and lead to hypercalcemia.
