Renal osteodystrophy in Egyptian CKD patients: observations from clinically indicated bone biopsies.

BACKGROUND

Renal osteodystrophy (ROD) varies among populations. Different genetic and environmental factors and prescription patterns may explain this variation. Egyptian ROD is not sufficiently studied. Although bone biopsy is the gold standard tool, no single study reported the actual ROD spectrum based on bone biopsy in Egypt or Africa. International guidelines must consider the different patterns in developing countries. METHODOLOGY: The ISN-sistership program enabled us to create an Egyptian bone biopsy consortium that provided a nationwide specialized CKD-MBD service. We included all CKD patients who were referred for unexplained bone pain, osteoporosis, or abnormal CKD-MBD laboratory parameters. Bone biopsy was offered for those who had clinical indications.

RESULTS

Over 2 years, 270 patients were recruited: 118 pre-dialysis, 97 on HD, 21 on PD, and 34 excluded. Non-invasive evaluation suggested that high bone turnover prevailed. Fourteen patients consented to the bone biopsy; all were on HD. Unexpectedly, various degrees of positive aluminum staining were present in 93% of biopsied patients, despite negative results in the dialysate water and nonuse of aluminum-based phosphate binders. Root cause analysis was done, triggering an environmental alarm for potential sources in food, water, and drug manufacturing. Aluminum-induced suppression of bone cells was confirmed by low turnover biomarkers in patients with significant aluminum accumulation. Moreover, FGF23 was significantly higher in the same group (z=-2.082, p-value = 0.037).

CONCLUSION

To conclude, Aluminum bone disease is still on the differential diagnosis list of ROD. Of the small biopsied patients, 93% had variable degrees of positive aluminum staining, and 57% had significant aluminum accumulation. Extra efforts are needed to eliminate this bone toxin.