Nephrol Dial Transplant (1989) 4: 1045-1053
© 1989 European Renal Association-European Dialysis and Transplant Association
research-article
Prevention of Osteitis Fibrosa, Aluminium Bone Disease and Soft-Tissue Calcification in Dialysis Patients: A Long-Term Comparison of Moderate Doses of Oral Calcium±Mg(OH)2 vs Al(OH)3±1
OH Vitamin D3
Hôpital Sud Amiens, France
Correspondence and offprint requests to: Correspondence and offprint requests to: Professor A. Fournier, Néphrologie, Hôpital Sud, CHU-BP 3009-80030 Amiens Cédex, France
Since 1980, moderately large doses of oral calcium (80±35 mmol/day as CaCO3±calcium polystyrene sulphonate), in association if necessary with Mg(OH)2 (2.5±1 g/day), with a reduction in the dialysate Mg concentrations from 0.75 to 0.375 mmol/24 h, have replaced Al(OH)3 as phosphate binders in our centre. Al(OH)3 was previously given to our haemodialysis patients in association with small doses of Ca CO3 (
3 g/day) and if necessary with 1
OH vitamin D3.
To compare the long-term-efficacy of this new approach with the former one in the prevention of renal osteodystrophy and soft-tissue calcification, 32 current patients were selected on the basis of at least 24 months of treatment in our centre and availability of a yearly bone survey (profile of lumbar spine and anteroposterior view of the pelvis, shoulders and hands). A group of 30 patients treated before 1980 were then selected on the same criteria and matched for age, sex, and duration on dialysis. Linear calcifications of the anterior and posterior walls of the aorta in front of L2, L3, L4 and on the lateral walls of the iliac and femoral arteries were measured and the paraarticular calcifications and subperiosteal resorptions of the hands evaluated.
The initial extent and the subsequent increase of the vascular and para-articular calcification were comparable in the two groups. Plasma alkaline phosphatase was stable in the normal range in both groups, as was plasma concentration of calcium. Plasma phosphate was slightly elevated (1.7 mmol/l) but stable and comparable in the two groups. In the Ca±Mg group plasma magnesium slightly increased from 1.2 to 1.4 mmol/l, whereas plasma aluminium decreased from 0.69 to 0.33 µmol/l. The other risk factors for vascular calcification were comparable in the two groups, namely systolic and diastolic blood pressure, and blood concentrations of cholesterol, triglycerides, uric acid and glucose.
A bone biopsy was performed in 13 of the Ca±Mg group and in 19 of the Al±1 group after a mean duration of observation of 2 years, i.e. after 56 months on dialysis. In the Ca±Mg group seven cases of osteitis fibrosa and four cases of non aluminic adynamic bone disease were diagnosed by this procedure. In the Al±1 group it diagnosed nine cases of osteitis fibrosa and four cases of adynamic bone disease with positive Aluminon staining at the calcified osteoid bone interface.
In conclusion, moderate doses of oral Ca±Mg(OH)2 are just as effective as Al(OH)3 associated with small doses of calcium and if necessary 1 OH vitamin D3 in controlling hyperparathyroidism. This is achieved without increased risk of soft-tissue calcifications as assessed on X-rays, provided hypercalcaemia and hyperphosphataemia are avoided. Since this approach avoids the hazards of aluminium intoxication, it represents a treatment of choice for the prevention of osteodystrophy in dialysed patients, but necessitates a weekly monitoring of predialysis plasma concentrations of calcium and phosphate.
Keywords: Oral calcium; Al(OH)3; Mg(OH)2; Hyperparathyroidism; Chronic haemodialysis; Soft-tissue calcification