Primary hyperparathyroidism: evaluated by 47calcium kinetics, calcium balance and serum bone-Gla-protein.

Combined 47Calcium kinetic and calcium balance studies with correction for dermal calcium loss were performed in thirteen patients with primary hyperparathyroidism (PHP), in whom serum bone-Gla-protein (S-BGP) was measured, and in ten matched controls. Dietary calcium was normal in PHP but both net (7.9 +/- 1.4 mmol Ca day-1 in PHP v. 3.5 +/- 0.9 mmol Ca day-1 in normals (mean +/- SE] and true (11.1 +/- 1.6 v. 6.8 +/- 0.9 mmol Ca day-1) intestinal absorbed calcium were enhanced (P less than 0.05). The renal calcium excretion (10.9 +/- 0.8 v. 5.1 +/- 0.4 mmol Ca day-1, P less than 0.001) and the dermal calcium loss (2.5 +/- 0.3 v. 1.5 +/- 0.1 mmol Ca day-1, P less than 0.02) were increased in PHP. Both patients and controls were in a negative calcium balance (P less than 0.01 and P less than 0.001, respectively) without any difference between the groups (P greater than 0.10). Mineralization (12.0 +/- 1.7 v. 4.8 +/- 0.8 mmol Ca day-1, P less than 0.02) and resorption rates (17.6 +/- 2.5 v. 7.9 +/- 0.6 mmol Ca day-1, P less than 0.02) were increased in PHP and S-BGP correlated positively to both variables (r = 0.64, P less than 0.05 and r = 0.62, P less than 0.05, respectively). Serum immunoreactive parathyroid hormone correlated positively to serum calcium (r = 0.69, P less than 0.01) but not to the calcium kinetic data.