Bone alterations in children and young adults with renal transplant assessed by phalangeal quantitative ultrasound

Abstract

Background: Bone alterations in young renal transplant recipients were investigated in several studies with conflicting results. Quantitative ultrasound of the phalanges is a recently developed noninvasive procedure to assess skeletal status.

Study design: Cross-sectional study at a single transplant center with values compared with previously studied healthy controls.

Settings & participants: 40 children and young adult recipients of renal grafts (15 females, 25 males; age, 20.0 +/- 8.4 years) studied 7.1 +/- 3.8 years after kidney transplantation.

Predictor: Clinical, biochemical, and therapeutic features, including calcium, phosphate, and intact parathormone levels; and cumulative dosages of glucocorticoids and cyclosporine administered since transplantation.

Outcome & measurement: Phalangeal quantitative ultrasound, including amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT), mainly dependent on mineral density and cortical thickness, respectively. Age- and sex-matched healthy controls were used to provide age-related z scores; sex- and height-matched healthy subjects, to provide z scores related to statural age.

Results: Mean z scores of AD-SoS and BTT were -0.05 +/- 1.59 and -0.54 +/- 1.17, respectively (P > 0.05 and P < 0.001, respectively). Multivariate analysis showed that AD-SoS z score was associated significantly with body mass index, intact parathormone level, cumulative glucocorticoids administered in the first posttransplantation year, and cyclosporine administered since transplantation (model r(2) = 0.79; P < 0.001); BTT z score was associated significantly with glucocorticoid dosage in the first posttransplantation year and age (model r(2) = 0.55; P < 0.001).

Limitations: Absence of other measures of bone structure and longitudinal measures and comparison to a noncurrent control group.

Conclusions: Children and young adults may have decreased cortical thickness with maintained overall mineral density after renal transplantation. The findings of phalangeal quantitative ultrasound parallel observations using other imaging techniques. Phalangeal quantitative ultrasound may be a useful method to assess bone alternations after renal transplantation.