RENAL BONE-DISEASE IN 76 PATIENTS WITH VARYING DEGREES OF PREDIALYSISCHRONIC-RENAL-FAILURE - A CROSS-SECTIONAL STUDY

Background. Renal osteodystrophy has been studied less extensively in predialysis than in dialysis patients. Different types of histological patterns in their natural evolution from moderate to advanced severit y of renal insufficiency are only partially known, with special regard to adynamic bone disease and its relationship with osteomalacia. Meth ods. We conducted a cross-sectional retrospective study on 76 unselect ed patients with chronic renal failure undergoing conservative treatme nt, with a wide range of severity of renal insufficiency. All the pati ents were subjected to bone biopsy for histological and histomorphomet ric evaluation. The patients, 44 males and 32 females ranging in age f rom 18 to 72 years and with serum creatinine 1.2-11.4 mg/dl, had not b een exposed to aluminium-containing drugs and had never been treated w ith vitamin D or calcitriol. Results. Ten patients had normal bone, ni ne were diagnosed with adynamic bone disease, 26 with mild mixed osteo dystrophy, seven with predominant osteomalacia, 22 with advanced mixed osteodystrophy, and two with predominant hyperparathyroidism. Patient s with adynamic bone disease had less severe chronic renal failure tha n the other pathological subgroups, intact PTH above the upper limit o f normal, normocalcaemia, and reduced serum osteocalcin in line with a significantly lower ObS/BS. Osteomalacia was found in a more advanced stage of chronic renal failure with relative hypocalcaemia and more s evere metabolic acidosis. A creatinine clearance of 20 ml/min served a s a clear demarcation between this histological group and adynamic bon e disease. Conclusions. It is postulated that adynamic bone disease is a form of renal osteodystrophy, separate from osteomalacia, appearing when bone resistance to PTH develops, probably a transient stage to m ore advanced hyperparathyroid histological classes with increasing sev erity of chronic renal failure.