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

BACKGROUND: Up until now, there was little known about the use of bone resorption markers in the assessment of bone status in patients with chronic renal failure (CRF). The present study evaluated the ability of a new immunoassay for N-terminal telopeptide of type I collagen to assess bone turnover in a group of hemodialyzed patients. METHODS: The following parameters were measured in a fasting blood sample from 111 patients on maintenance hemodialysis for at least 2 years and in 120 healthy subjects: calcium, phosphorus, magnesium, BALP, PTH, and N-terminal telopeptide of type I collagen (NTx-ELISA, OSTEOMARK NTx Siero-Ostex International). RESULTS: Serum PTH, BALP, and NTx were significantly higher (P<0.001) in hemodialyzed (HD) patients than in healthy subjects. In HD patients, PTH was correlated to BALP and NTx (r=0.40 and 0.55, respectively). When combining PTH and BALP serum levels, 17 patients showed high turnover (HT) and 65 were found to have a normal to low turnover (N-LT). In HT patients, serum NTx and dialytic age were significantly (P<0.01) higher than in N-LT patients. Moreover, even after adjusting for age, body mass index, dialytic age, and calcium-vitamin D treatment, serum NTx discriminated between HT and N-LT with a sensitivity of 97.6% and a specificity of 90.9%. CONCLUSION: Although bone biopsy remains the reference method for the diagnosis of renal osteodystrophy, the combined use of markers of bone resorption and bone formation could improve the clinical management of renal bone diseases.

Heel ultrasonography in monitoring alendronate therapy: a four-year longitudinal study.

The possibility of using quantitative ultrasound (QUS) in monitoring the response to antiresorptive drugs has yet to be defined. The aim of the present study was to evaluate whether heel ultrasonography, considering its characteristics of long-term precision, is able to monitor osteoporotic patients treated with alendronate. We studied 150 postmenopausal osteoporotic women (age 59.6 +/- 5.3 years) treated with alendronate and calcium (n = 74) or with calcium alone (n = 76) for 4 years. At baseline and after 12, 24, 36 and 48 months, we measured bone mineral density (BMD) at the lumbar spine by dual-energy X-ray absorptiometry (DXA, Hologic 4500), and speed of sound (SOS), broadband ultrasound attenuation (BUA) and Stiffness at the calcaneus by Achilles plus. Moreover, the longitudinal precision of QUS parameters was assessed by measuring 10 subjects once a month for 1 year and, on the basis of the coefficients of variation we obtained, we calculated the Least Significant Change between two measurements. In the alendronate-treated patients, at year 1, BMD increased by 4.2%, SOS by 0.4%, BUA by 1.1% and Stiffness by 3.2%; at year 2, BMD increased by 5.0%, SOS by 0.7%, BUA by 1.4% and Stiffness by 5.7%. At year 3, BMD increased by 6.2%, SOS by 0.9%, BUA by 1.8% and Stiffness by 7.6%. At the end of the study period, BMD increased by 7.6%, SOS by 1.2%, BUA by 1.9% and Stiffness by 9.0%. The minimal significant difference between two measurements was 0.8% for SOS, 5.6% for BUA and 5.0% for Stiffness. Among the QUS parameters, Stiffness showed the greatest total treatment effect and a longitudinal sensitivity which was only slightly lower than BMD. The MTI, which represents the period between scans required to show that a 'true' change has occurred, was 1.8, 2.7, 11.9 and 2.2 years for BMD, SOS, BUA and Stiffness respectively. Therefore, although the spinal BMD remains the optimal method, QUS at the heel, and in particular Stiffness, seems to be a sensitive tool for monitoring the response to alendronate.

Usefulness of bone quantitative ultrasound in management of osteoporosis in men.

In order to evaluate the usefulness of QUS at the phalanx in the diagnosis of osteoporosis and in the prediction of fracture risk in males. The study consisted of 182 subjects (age 61.2 +/- 9.4 yr), of which 22 had had a previous nontraumatic bone fracture. In all subjects, bone mineral density (BMD) at the lumbar spine and femur was measured by DXA. Moreover, in the same subjects, QUS parameters, the amplitude-dependent speed of sound (AD-SOS), and the parameters characterizing the graphic trace (fast-wave amplitude, signal dynamic, and bone transmission time [BTT]) were assessed at the phalanxes using the DBM Sonic 1200 (IGEA). According to World Health Organization (WHO) criteria, all the patients were divided into two groups: 62 osteoporotic subjects and 120 nonosteoporotic subjects. All QUS parameters were significantly lower in osteoporotic than in nonosteoporotic patients. Receiver operating characteristic (ROC) analysis showed a moderate ability of AD-SOS, BTT, and ultrasound bone profile index (UBPI) in distinguishing between healthy and osteoporotic men. Among osteoporotic patients, BMD values were lower in patients with fracture than in those without fracture. AD-SOS and BTT were significantly reduced in men with fracture. Furthermore, in a regression analysis, only BTT and DXA parameters were predictive of fracture. Moreover, performing a multivariate regression analysis BTT entered before BMD at the lumbar spine and at Ward's triangle. In conclusion, our data show that QUS parameters are reduced in osteoporotic males; however, only BTT was comparable to DXA parameters in the prediction of fracture risk in men.

Quantitative ultrasound at the phalanges in healthy Italian men.

In the last decade there has been a growing interest in quantitative ultrasound (QUS) techniques as a new method in the assessment of bone status in metabolic bone diseases. Many studies have shown that QUS parameters can predict vertebral and femoral fracture risk in patients with osteoporosis. However, most of the studies were performed in women, whereas few data are available for men. The aim of this study was to build up a normative database on a healthy Italian male population for QUS parameters at the phalanges. Amplitude-dependent speed of sound (AD-SoS) and three parameters (first wave amplitude, FWA; signal dynamic, SDy; time frame, TF) characterizing the graphic trace of the ultrasound signal were measured at the phalanges in 286 healthy subjects (age range 20-87 years). First, the QUS device was adapted to compensate for the difference in finger thickness between men and women. Preliminary data on 150 healthy subjects showed a significant difference between the traditional and adapted device, and the latter was independent of finger thickness variations. AD-SoS showed a significant (p<0.001) decrease with aging, expressed by a second-order polynomial equation. The peak value (2122 m/s) was observed in the fourth decade; thereafter it decreased to 1980 m/s at the ninth decade. Likewise, FWA and SDy were significantly (p<0.001) reduced after the fourth decade, whereas TF remained stable over time until the last decade. In conclusion, in men AD-SoS showed a negative trend with aging. The pattern with aging of parameters characterizing the graphic trace was different from the pattern for AD-SoS, suggesting the possibility of obtaining further information on phalanx bone physical properties which could be useful in the differential diagnosis of metabolic bone diseases and in the assessment of fracture risk.