Ionic Calcium Determination in Primary Hyperparathyroidism

Abstract

Serum ionic and total calcium levels were measured in 15 patients with clinical diagnosis of primary hyperparathyroidism. Ionic calcium level was measured by a calcium-selective liquid-membrane electrode and total calcium level was measured by atomic absorption spectroscopy. Concurrent determinations of ionic and total calcium in 230 blood donors served as normal values. Of the determinations of ionic calcium in the hyperparathyroid patients, 98.5% (67 of 68) fell outside the normal range of 4.48 to 5.28 mg/100 ml, while 77% (57 of 74) of the determinations of total calcium in the same patients was outside the normal range of 8.3 to 10.1 mg/100 ml. Parathyroid adenomas or hyperplasia were found in 14 of 15 patients. The calcium-selective electrode has proven to be highly discriminatory in separating hypercalcemia from normocalcemia in patients with primary hyperparathyroidism.