Bone mineral density in children with primary hyperoxaluria type I

Abstract

Background. In primary hyperoxaluria type I (PH 1), hepatic overproduction of oxalate leads to its deposition in various organ systems including bone (oxalosis). To evaluate skeletal status non-invasively in PH 1 we measured bone mineral density (BMD). Methods. Peripheral quantitative computed tomography of the distal radius was performed in 10 children with PH 1 (mean chronological age 9 ± 3.1, mean skeletal age 8.3 ± 3.0 years): seven were on conservative treatment (CT) including one patient after pre-emptive liver transplantation (PH1-CT) and three were studied with end-stage renal disease on peritoneal dialysis (PH1-ESRD). Results. Mean trabecular bone density (TBD) was significantly increased in PH1-ESRD compared with both age-matched healthy and uraemic controls (65227 vs 168 ± 63 and 256 ± 80 mg/cm3; P < 0.002 and P < 0.007, respectively), while cortical bone density (CBD) was elevated to a lesser degree (517 ± 23 vs 348 ± 81 vs 385 ± 113 mg/cm3; P < 0.02 and P < 0.04, respectively). In PH 1, CBD and, even more so, TBD were significantly correlated with serum creatinine (r = 0.91 and r = 0.96, P < 0.0001, respectively) and plasma oxalate levels (r = 0.86 and r = 0.94, P < 0.001 and P < 0.0001, respectively). In children with PH 1 and normal glomerular function, both CBD and TBD were comparable with healthy controls. Conclusion. These preliminary data suggest that in PH 1 BMD is significantly increased in ESRD, probably due to oxalate disposal. Measurement of BMD may be a valuable and non-invasive tool in determining and monitoring oxalate burden in this disorder.