prevalence of hypercalcemia and hypercalciuria in thyrotoxic patients of a referral endocrine clinic

many patients with thyrotoxicosis develop hypercalciuria and nypercalcemia. urine calcium excretion depends on diet, latitude and sunshine exposure. with regard to variation of these indices in different geographical regions, we conducted a one-year study on 202 patients, 65 males and 137 females, with thyrotoxicosis of varying severity. the mean age of patients was 35.24±11.95 and 35.87±12.21 years for men and women respectively. free t4 index, serum calcium and phosphorus, pth and alkaline phosphatase were measured in all patients. the mean for fti was 7.48±1.98. serum ca and p mean was 9.31±0.46 mg/dl and 4.11±0.61 mg/dl respectively. 3 patients (1.5%) had hypercalcemia and hyperphosphatemia was detected in 38(18.6%) patients. the mean of urine ca and p were 190±106.7 mg/24h and 626±246.73 mg/ 24h respectively. increased urine ca and p was detected in 20(9.8%) and 4(4.4%) patients respectively. pth was suppressed in 34(16%) and alkaline phosphatase was increased in 50(24.5%) patients. there was no significant relation between fti with serum and urine ca and p and serum pth and alkaline phosphatase in thyrotoxic patients. there was also no appreciable difference in serum ca and p and urine ca between the two sexes with respect to the lower exposure of muslim women to sunlight. these results contrast with the high frequency of hypercalcemia (27%) and hypercalciuria in patients with thyrotoxicosis in previous studies and might be due to habitual low calcium diet and sunshine exposure in this area.