Pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen in uremic hyperparathyroidism

SUMMARY: We compared the serum level of the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (I-CTP) with clinical parameters of bone formation and skeletal symptoms to investigate whether I-CTP can predict the degree of renal osteodystrophy. Serum I-CTP was measured in 41 patients with secondary hyperparathyroidism who underwent total parathyroidectomy and autoimplantation (PTx). Measurement was done by using radioimmunoassay. Blood samples were collected before surgery and at 1, 3, 6, 9, 12, 15, and 18 months afterwards for the measurement of bone formation parameters. Serum I-CTP levels were significantly higher in patients with Jensen grade 3–5 renal osteodystrophy than in patients with grade 0–2 renal osteodystrophy. the I-CTP levels were also significantly higher in patients with bone or joint pain compared with patients without pain. There was a significant negative correlation between the serum I-CTP level and the lumbar vertebral (L2-4) bone mineral density. Serum I-CTP was significantly correlated with the serum levels of alkaline phosphatase, calcium, and phosphate, as well as the serum calcium x phosphate product, and the intact parathyroid hormone level. These findings suggest that serum I-CTP could be used as a marker for evaluating osteodystrophy in uremic hyperparathyroidism.