To evaluate bone loss in renal osteodystrophy, we measured total and regional (head, trunk, pelvis, leg and arm) bone mineral density (BMD) by dual photon absorptiometry in 72 patients on maintenance hemodialysis (HD). We also examined the validity of serum carboxy-terminal parathyroid hormone (C-PTH) and intact-PTH as an indicator of secondary hyperparathyroidism. Total BMD correlated inversely with age in female patients (r = -0.57, p less than 0.01), but not in male patients. Female patients older than 50 years were omitted from analysis to exclude the effect of menopause on bone. Among clinical and biochemical parameters, only trunk BMD correlated inversely with the duration of HD (r = -0.26, p less than 0.05). Head, trunk and total BMD correlated inversely with serum alkaline phosphatase, C-PTH and intact-PTH, while pelvis BMD did not. Leg and arm BMD also correlated inversely with serum intact-PTH, but not with serum C-PTH. The serum level of C-PTH correlated positively with the duration of HD (r = 0.40, p less than 0.005), while intact-PTH did not. As compared with 18 control male volunteers aged 25-42 years, trunk, pelvis, leg, arm and total BMD were significantly lower in male patients on HD aged 22-49 years, whereas head BMD did not differ significantly between the two groups. The percent decrease of BMD was most prominent in the trunk (-19.6%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)