Differential diagnosis between secondary hyperparathyroidism and aluminum intoxication in uremic patients: usefulness of 99mTc-pyrophosphate bone scintigraphy

Abstract

Forty-one patients in chronic end-stage renal failure and 4 patients with a functioning kidney transplant presented with spontaneous hypercalcemia or intolerance to vitamin D3 sterols and/or oral calcium supplements. Bone iliac crest biopsy with aluminum staining and Tc-pyrophosphate bone scintigraphy with determination of Fogelman score were performed in all cases. Two patients had aluminum-induced osteomalacia (AL O). Thirty-eight biopsies showed renal osteodystrophy (secondary hyperparathyroidism or various combinations of osteitis fibrosa and osteomalacia): 19 with positive staining for aluminum (RO + AL) and 19 without aluminum deposits (RO). The series also comprised 2 cases of pure osteomalacia (OM), 2 cases of osteoporosis (OP), and 1 case of osteoporosis with aluminum accumulation (OP + AL). Mean Fogelman score in RO patients (9.1 +/- 0.3) was significantly higher than in all other categories (5.9 +/- 0.5 for RO + AL, and scores ranging from 0 to 8 in the last 7 patients, p less than 0.01). Patients with massive aluminum accumulation in bone (greater than 75% of the total trabecular surface) showed no or very low uptake of the isotope by the skeleton. Fogelman scores of 9 or higher were always associated with histological secondary hyperparathyroidism. 99mTc-pyrophosphate bone scintigraphy is helpful to distinguish aluminum intoxication from secondary hyperparathyroidism in uremic patients.