[Serum osteocalcin level as a marker of the functional state of osteoblasts after oral calcium tolerance test].

The results are presented of an oral calcium tolerance test with 1,000 mg calcium in 20 patients with recurrent renal calcium calculosis, a woman with primary hyperparathyroidism and incipient renal failure (serum creatinine 1.8 mg%), creatinine clearance 55 ml/min) and 9 healthy persons as controls. The serum osteocalcin level was determined before and after the oral test. The results show that the serum osteocalcin level alone is of no differential diagnostic value for differentiation of the various types of hypercalciuria in patients with recurrent renal calcium calculosis. As a marker of osteoblasts functional state however the determination of serum osteocalcin level is of great importance for the early diagnosis of osteoporosis. In 3 patients with renal hypercalciuria, often leading to general osteoporosis, an acute rise of serum osteocalcin level was found after the oral calcium tolerance test. High osteocalcin level was also found in the patient with primary hyperparathyroidism and incipient renal failure.