BONE DENSITOMETRY IN PATIENTS ON PERITONE AL-DIALYSIS

Bone densitometry is being validated as an adequate method to study so me aspects of renal osteodystrophy. We have studied bone densitometry in 33 patients (18 of them diabetics) with chronic renal failure treat ed with continuous ambulatory peritoneal dialysis (CAPD). The mean age of the group was 55,9 years and the mean time on dialysis was 13,7 mo nths. Bone mineral density (BMD) was measured by means of dual energy x-ray absorptiometry (DEXA) and the measurements was done on lumbar sp ine (trabecular bone) and on femoral neck (trabecular and cortical bon e). Radiological and biochemical (serum calcium, serum phosphate, alka line phosphatase, osteocalcin and intact parathyroid hormone iPTH) stu dies were performed at the same time. Z-score of BMD was calculated in each patient. Analysis of data showed that male patients on CAPD has reduced values of BMD at lumbar spine and at femoral neck. Female pati ents only showed reduced BMD at femoral neck. There was no correlation of BMD with time on dialysis. There was no difference in BMD nor in z -score of BMD between diabetics and non-diabetics. We have found a pos itive correlation between z-score of BMD and serum calcium and an inve rse correlation with iPTH and osteocalcin. Low values of BMD were asso ciated to radiological findings of osteopenia. In conclusion, bone den sitometry is a valuable method to detect changes in bone mass in patie nts with chronic renal failure treated with CAPD and could be useful i n the follow up of renal osteodystrophy. The inverse relationship betw een BMD and bone markers could be related with the continuous supply o f calcium through the dialysate occurring in CAPD, that acting on PTH levels could have influence on BMD.