Bone histomorphometry and serum bone gla-protein in the diagnosis of primary hyperparathyroidism.

Abstract

AbstractThe diagnosis of primary hyperparathyroidism (PHP) may be difficult, especially in the case of asymptomatic hypercalcemia. Since bone is the major target organ of parathyroid hormone (PTH), the hypersecretion of PTH in patients with PHP can be assessed by bone biopsy and by measured markers of bone turnover. In a first study, a transiliac bone biopsy was performed in 184 patients with surgically proven parathyroid adenoma (159 cases) or parathyroid hyperplasia (25 cases), and quantitative measurements were compared with age‐and sex‐matched controls. In patients with parathyroid adenoma, there was a marked and significant increase of the resorption surfaces, the area of the periosteocytic lacunae, and the osteoid surfaces measured on the trabecular bone. Similar results were found in patients with parathyroid hyperplasia. Only 4 patients (2.2% of cases) had a normal bone biopsy, indicating that bone histomorphometry is a sensitive method for detecting an increase of bone turnover in PHP. However, this method is not specific and does not differentiate between primary and secondary hyperparathyroidism.In a second study, we measured serum bone gla‐protein (sBGP), also called osteocalcin, which is a new specific marker of bone turnover, in 25 patients with primary hyperparathyroidism: sBGP was increased (14.2±9.6 ng/ml versus 6.2±2.4 ng/ml in controls, p<0.001) and was significantly correlated with serum PTH, serum calcium, and adenoma weight. In the patients who had a simultaneous bone biopsy, sBGP was found to be significantly correlated with the parameters reflecting bone formation. In conclusion, bone histomorphometry and measurement of sBGP are 2 sensitive methods for detecting increased bone turnover in patients with PHP. These methods may be useful for the diagnosis of PHP when other biochemical tests fail.