Ionized and total serum calcium and parathyroid hormone in hyperthyroidism.
Total and ionized calcium concentrations as well as parathyroid hormone levels were measured in a group of hyperthyroid persons. Ionized and total calcium levels were elevated in 21 of 45 (47%) and in 12 of 45 (27%) thyrotoxic patients, respectively. Mean ionized and total calcium levels were higher in these 45 patients than in normal persons. Using two different radioimmunoassay systems for a total of 44 determinations, mean parathyroid hormone levels were lower in thyrotoxic patients than in subjects with proved hyperparathyroidism. These data suggest that [1] elevations of both ionized and total calcium concentrations occur frequently in thyrotoxic patients; [2] ionized calcium concentrations may be elevated in a higher percentage of hyperthyroid subjects than are total calcium concentrations; and [3] the hypercalcemia associated with thyrotoxicosis is not associated with elevated parathyroid hormone levels.
D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood*; D007106:Immune Sera; D007477:Ions; D010281:Parathyroid Hormone / Q000097:blood*; D011247:Pregnancy
D007106:Immune Sera; D007477:Ions; D010281:Parathyroid Hormone; D002118:Calcium