A new serum assay to measure N-terminal fragment of telopeptide of type I collagen in patients with renal osteodystrophy

Response of serum carboxylated and undercarboxylated osteocalcin to risedronate monotherapy and combined therapy with vitamin K(2) in corticosteroid-treated patients: a pilot study

OBJECTIVE

The aim of this study was to investigate the responses of serum osteocalcin (OC), undercarboxylated osteocalcin (ucOC) and N-terminal telopeptide of type I collagen (NTx) to corticosteroids, and to examine the effects of risedronate therapy with or without vitamin K(2) supplementation on bone metabolic markers in corticosteroid-treated patients.

METHODS

Sixteen patients on corticosteroid therapy for neuromuscular disorders were assigned randomly to 2 groups (A: risedronate monotherapy, n=8; B: combined risedronate and vitamin K(2) therapy, n=8) and treated for 1 year. Another 6 patients who received intravenous steroid pulse therapy were assigned to group C for investigation of the effects of corticosteroids on OC and ucOC 1 month after pulse therapy.

RESULTS

Serial measurements revealed that significant decreases of OC, ucOC and NTx persisted with a similar time course profile during 1 year of treatment in groups A and B, and between-group analysis failed to demonstrate any additional effects of vitamin K(2) on risedronate therapy. Intravenous steroid pulse therapy induced a transient depression of OC and ucOC within 1 week in group C.

CONCLUSION

These results indicate that serum concentrations of OC and ucOC become consistently low during corticosteroid administration despite risedronate therapy with or without vitamin K(2) supplementation, and the serum ucOC level may not be a reliable indicator of vitamin K status under corticosteroid administration.

Correlation between parathyroid hormone, bone alkaline phosphatase and N-telopeptide of type 1 collagen in diabetic and non-diabetic haemodialysis patients

BACKGROUND

Haemodialysis (HD) patients with diabetes mellitus often have renal osteodystrophy (ROD) characterized by reduced bone turnover, but little is known about the correlation between bone formation and bone resorption in this population.

METHODS

The authors measured serum parathyroid hormone (PTH), bone alkaline phosphatase (BAP), N-telopeptides of type 1 collagen (NTx) and fasting glucose in 48 patients with diabetic nephropathy (DN) and 80 patients with glomerulonephritis (non-DN) who had received <or=10 years of regular HD. Spearman's correlation coefficients (r) were derived.

RESULTS

In the whole patients, the DN group had a lower PTH and NTx level than the non-DN group. Serum PTH was not correlated with NTx in the DN group, whereas all three markers were correlated with each other in the non-DN group. Subdividing the DN patients according to HD duration revealed remarkable differences in the correlation between BAP and NTx: in patients receiving >or=5 years HD (r = 0.568) this correlation was similar to that in the non-DN group (r = 0.653), whereas there was no significant correlation in those receiving <5 years HD. Patients receiving >or=5 years HD had a comparable glucose level (111.1 +/- 19.2 mg/dL) to the non-DN group, whereas those receiving <5 years had a higher level (196.1 +/- 53.1 mg/dL).

CONCLUSION

Differences in the interaction between bone cells between DN and non-DN patients are one potential cause of lower bone turnover in the former group. Research of this correlation is needed to increase understanding of the complexities of bone metabolism in DN patients.

The clinical significance of serum osteocalcin and N-terminal propeptide of type I collagen in predialysis patients with chronic renal failure

Several new serum markers for bone metabolism have recently become available and are being applied to clinical practice. Their clinical usefulness in predialysis patients with chronic renal failure (CRF), however, has not yet been determined. Serum levels of three bone formation markers-bone alkaline phosphatase (BAP), osteocalcin (OC), and N-terminal propeptide of type I collagen (PINP)-and three bone resorption markers-type I collagen cross-linked N-telopeptide (NTx), deoxypyridinoline (DPD), and pyridinoline (PYD)-were measured simultaneously in 85 predialysis CRF patients (serum creatinine 3.5 +/- 1.9 mg/dl, 61.0 +/- 10.9 years old, 54 males and 31 females, 36 diabetics and 49 nondiabetics) to examine the relationships between these markers and bone mineral density (BMD) of the distal radius, as measured by peripheral quantitative computed tomography (pQCT). Trabecular BMD, which is strongly affected by bone metabolism, was significantly negatively correlated with each of the bone formation markers (r=-0.341, p=0.0016, for OC; r=-0.314, p=0.0036, for PINP; r=-0.238, p=0.0315, for BAP), but there was no significant correlation between BMD and any of the bone resorption markers. In multivariate regression analyses (adjusted by age, sex, presence of diabetes, glomerular filtration rate, intact parathyroid hormone, calcium, phosphate, and 1,25-dihydroxyvitamin D), OC and PINP were significantly associated with a decrease in BMD, but BAP was not. In conclusion, we demonstrated that in predialysis CRF patients, BMD of the distal radius, particularly of trabecular bone, is associated with serum OC and PINP levels. OC and PINP are suggested to be possible parameters for the clinical evaluation of the effect of bone metabolism on BMD.

Serum cross-linked N-terminal telopeptide of type I collagen for evaluation of renal osteodystrophy in hemodialysis patients

BACKGROUND

Useful markers of bone resorption are needed for hemodialysis patients with renal osteodystrophy. This study investigated the use of a new immunoassay for cross-linked N-terminal telopeptide of type 1 collagen to assess bone changes in hemodialysis patients.

METHODS

Radial bone mineral density was examined in 178 hemodialysis patients at baseline and after 12 months. Serum levels of N-terminal telopeptide and other markers were measured.

RESULTS

The annual percent change of radial bone mineral density was negatively correlated with the levels of N-terminal telopeptide, intact osteocalcin, tartrate-resistant acid phosphatase, bone-specific alkaline phosphatase, and intact parathyroid hormone. The annual percent change of radial bone mineral density showed a stronger correlation with N-terminal telopeptide levels than with the other markers, except for intact parathyroid hormone. Also, intact parathyroid hormone and N-terminal telopeptide levels showed a stronger correlation than that of either tartrate-resistant acid phosphatase or cross-linked carboxyterminal telopeptide of type 1 collagen with intact parathyroid hormone.

CONCLUSION

Serum N-terminal telopeptide may be the most useful bone resorption marker in renal osteodystrophy and its use combined with bone formation markers may improve the management of this condition.