[A case of esophageal carcinoma with hypercalcemia caused by PTH-rP--the effect of therapy on the bone and calcium metabolism].

The changes in the bone and in calcium metabolism during cisplatin or bisphosphonate administration is reported in a 50-year-old patient with esophageal carcinoma who had humoral hypercalcemia of malignancy (HHM). Laboratory findings on admission showed that ionized calcium was 1.65mmol/L, phosphorus was 2.4mg/dl, and PTH-rP was 151pmol/L, without any evidence of bone metastasis. After admission, cisplatin and/or bisphosphonate were administrated for hypercalcemia. These administrations ameliorated serum ionized calcium, urinary pyridinoline and hydroxyproline level within a few days. Although cisplatin administration decreased the serum osteocalcin level, bisphosphonate administration kept up the level, suggesting that bisphosphonate maintained bone formation and cisplatin decreased its formation. The discrepancy may be due to the coupling with the reduction of bone resorption and/or direct toxic effect on osteoblasts during cisplatin administration, and preservation of osteoblastic activity during bisphosphonate administration. Cisplatin and bisphosphonate may have different effects on bone formation. Serum 1,25(OH)2D level was slightly decreased or unchangeable after cisplatin administration, although the level was increased after bisphosphonate administration. Direct toxic effect on 1 alpha-hydroxylase of the kidney or increase in phosphrous level may explain the change of 1,25(OH)2D after cisplatin administration. These results suggested that cisplatin and bisphosphonate have the same effect of preventing bone resorption but different effects on bone formation and/or serum 1,25(OH)2D level.