HIGH-FREQUENCY OF IRON BONE DEPOSITS IN A MEXICAN POPULATION WITH RENAL OSTEODYSTROPHY

Renal osteodystrophy (ROD) is a multifactorial disease. Aluminium depo sits have been implicated in its physiopathology but iron deposits hav e seldom been described. The purpose of this study was to investigate the presence of iron on the mineralization front, in 70 patients with ROD. Their mean age was 48 +/- 16 years, 36 were female, 34 male, 55 w ere admitted on peritoneal dialysis (78.5%) and 15 to haemodialysis (2 1.5%). for a period of 28 +/- 22 months. A bone biopsy was obtained fr om each patient after double tetracycline labelling. Blood samples wer e also obtained at the time of bone biopsy. The histomophometric analy sis was performed following the criteria of Sherrard et at., with slig ht modifications; beside the usual stains, aluminium, iron and amyloid stainings were done on all bone specimens. Biochemical findings were: Ca 8.8 +/- 0.9 mg/dl, P 6.1 +/- 1.5 mg/dl; total alkaline phosphatase 197 +/- 258; PTHm 4.9 +/- 4.05 ng/ml (normal 0.4-0.7 ng/ml), calciton in 11 +/- 6 pg/ml (normal 1-26 pg/ml). Osteitis fibrosa was found in 3 1 patients (44.28%), mixed bone disease in two patients (2.28%); mild bone disease in 20 subjects (28.57%), adynamic bone lesion in 15 cases (21.42%) and osteomalacia in two patients (2.28%). iron deposits were found on the mineralization front in 43 patients (61.4%); in 17, the percentage was <25 and, in 26, >25%. The iron deposits in the osteitis fibrosa group were highly significant (25/31). The aluminium deposit at the mineralization front was observed in eight patients (11.4%); in all but one, the percentage of this metal was <10%. Amyloid deposits were negative in all cases. The results show: (i) a Mexican population with ROD, present a highly significant incidence of siderosis on the bone mineralization front: (ii) in contrast, the aluminium deposits in this group of patients is lower than that reported in other series, a nd (iii) the spectrum of RO in this Mexican population is similar to t hat reported in other studies.