The causes of hypercalcemia in Okinawan patients: an international comparison.

OBJECTIVE Our objective was to determine the causes and relative prevalence of hypercalcemia in patients at a major community hospital in Okinawa, Japan. Additionally, we compared these causes of hypercalcemia with the previously published international data. MATERIALS AND METHODS We analyzed all patients with hypercalcemia in a community teaching hospital in Okinawa, Japan, from 1999 to 2002 and determined the cause of hypercalcemia in each patient. We also performed a literature review of the original articles describing causes of hypercalcemia in patients from Eastern as well as Western countries. RESULTS We identified 145 patients with hypercalcemia (median age, 69; range, 22 to 97). Major causes included malignant disorders (n=100; 69%), primary hyperparathyroidism (n=31; 21%), vitamin D-induced (n=4; 3%), and miscellaneous or unknown cause in 11 (8%). Among malignant disorders, adult T cell leukemia was the most frequent (n=35), being followed by lung cancer (n=25). Breast carcinoma was less prevalent (n=4). CONCLUSION The major causes of hypercalcemia are malignancy and primary hyperparathyroidism in Okinawan Japanese patients. Adult T cell leukemia and lung carcinoma are among the top leading malignancies, while breast carcinoma is less frequent in this patient population. The etiologic prevalence of hypercalcemia in the Eastern population including Okinawans is significantly different from that in the Western population.