Bone loss after renal transplantation: role of hyperparathyroidism, acidosis, cyclosporine and systemic disease

In order to determine risk factors for bone loss after renal transplantatio n, dual energy X-ray absorptiometry was performed in 125 renal transplant p atients. The bone mineral density (BMD) was expressed as a percentage of th e normal population (BMD%) and Z-score (SD from normal). The whole body, lu mbar spine and femoral neck BMD% (Z-score) values were 93.9 +/- 8.9 ( - 0.9 0 SD), 91.6 +/- 14.9 ( - 0.98 SD) and 87 +/- 15.3 ( - 1.0 SD)%, respectivel y. Low BMD% was associated with low creatinine clearance ( < 40 mL/min: 91. 6 +/- 7.9, > 40 mL/min: 95.6 +/- 8.0, p < 0.01), repeated graft loss (0: 94 .4 +/- 9.1, > 1: 87.4 +/- 9.3, p < 0.05), long dialysis duration (< 1 yr: 9 5.2 +/- 7.9, > 5: 90.1 +/- 10.6, p <0.05), acidosis (bicarbonate < 21 mmol/ L: 89.6 +/- 8.0, > 27: 96.7 +/- 7.2, p < 0.01), secondary and tertiary hype rparathyroidism (< 50 ng/L: 95.9 +/- 7.1, > 200: 87.7 +/- 5.0, p < 0.01), r aised alkaline phosphatase ( < 200 units/L: 95.7 +/- 7.2, > 300: 85.6 +/- 1 3.2, p < 0.001), osteocalcin (< 50 mu g/L: 95.2 +/- 6.7, > 100: 89.3 +/- 7. 6, p < 0.01) and urinary deoxypyridinoline (< 5 nM/mM creatinine: femoral n eck 89.6 +/- 10.7, >10: 82.1 +/- 20.1, p < 0.05), low 25-OH-vitamin D ( < 1 0 mu g/L: 91.3 +/- 9.8, > 20: 96.9 +/- 7.4, p < 0.001) and high cyclosporin e concentration (0 ng/L: 98.3 +/- 7.0, > 150: 92.1 +/- 9.3, p < 0.05). Pati ents with clinical atherosclerosis (91.7 +/- 8.6 vs. 95.4 +/- 8.8, p < 0.01 ), hypoalbuminemia (< 550 mu mol/L: 87.6 +/- 13.2, > 550. 94.2 +/- 7.8, p < 0.01), renovascular disease (89.7 +/- 5.7 vs. 95.0 +/- 5.7, p < 0.05) and diabetic nephropathy (femoral neck 76.6 +/- 8.8 vs. 89.3 +/- 15.1, p < 0.01 ) had lower bone masses. High bone mass was associated with previous dialys is alphacalcidol therapy (0: 92.2 +/- 7.5, > 3 mu g/wk: 97.3 +/- 6.9, p < 0 .05). No relationships with transplantation duration, 1,25-OH-vitamin D, al uminium, calcium or steroid dose were found. No involutional changes in ter tiary hyperparathyroidism could be discerned. Conclusion. The major threats to bone mass after renal transplantation appe ar to be ongoing hyperparathyroid bone disease, low renal function, acidosi s, systemic disease and hypo-vitaminosis D.