The NTX assay in the follow-up of the osteoporotic patients: 3 years of alendronate treatment

These studies were conducted on 38 female patients treated with alendronate (10 mg/day, per os) for 3 years, because of osteoporosis. Of these patients, 29 were in the menopausal age longer than 10 years, and the remaining nine patients were in menopausa shorter than 10 years. Urine sample were taken at the start of the treatment and every 6 months afterward for 3 years, and crosslinked N-telopeptides of type I collagen (NTx) have been measured in them by means of an ELISA technique. Bone mineral density (BMD) has been recorded at the ultradistal (UDBMD) and mediodistal (MDBMD) region of radius of the non-dominant side. Body mass index (BMI) of the subjects has also been determined each time. The baseline values of NTx varied very much, scattered in a range of 11–215 nanomoles bone collagen equivalent/millimoles creatinine (nM BCE/mM Cr), in average 59±46; those of UDBMD and MDBMD amounted to 258±63 and 587±112 mg/cm2, respectively. NTx, the BMD values and the menopausal age does not correlate with cach other. Both BMD values increased almost linearly in the total study pool during the 3-years-long treatment, being 3.0–9.2 and 0.8–2.5% higher in terms of UDBMD and MDBMD, respectively. Urine NTx concentrations decreased during the same time 30–35%. It is concluded that monitoring of urine NTx levels may be very useful during antiosteoporotic treatments, because a reduction of NTx is an indicator of the slowing down of bone turnover and the bone losses, as was observed during the alendronate therapy.