Quantitative heel ultrasound in assessment of bone structure in renal transplant recipients

Many patients with advanced renal disease have osteopenia or even osteoporo sis by the definition of the World Health Organization based on bone minera l density (BMD). Dual-energy X-ray absorptiometry (DXA), the standard metho d to assess BMD, is not always available. Quantitative heel ultrasound (QUS ) is an inexpensive, mobile, and radiation-free diagnostic alternative, yet few data address this method's usefulness in patients with renal disease. The present study assessed the value of QUS in detecting changes in bone st ructure in renal transplant recipients compared with DXA. In a cross-sectio nal analysis, 50 patients (29 women) with a mean age of 50 +/- 13 years, me an time since transplantation of 60 months (range, 1 to 205 months), and st able renal allograft function were studied, BMD was quantified by DXA of th e hip and spine. QUS of the left heel measured broadband ultrasound attenua tion (BUA) and speed of sound (SOS). Stiffness index (SI) was calculated as SI = (0.67 * BUA + 0.28 * SOS) - 420. DXA measurements established the dia gnoses of osteopenia and osteoporosis in 49% and 22% of the patients, respe ctively. Femoral neck BMD and QUS parameters showed good correlation (r = 0 .638; P < 0.001). Sensitivities of BUA, SOS, and SI for diagnosing osteopor osis were 100%, and specificities were 73%, 76%, and 78%, respectively. Pos itive predictive values were 50%, 53%, and 56%, and negative predictive val ues were 100%. QUS can be recommended for screening patients who do not hav e osteoporosis. Those suspected of osteopenic bone structure should be exam ined by additional DXA measurement for quantification before initiation of therapy. (C) 2001 by the National Kidney Foundation, Inc.