RENAL OSTEODYSTROPHY DURING THE DEVELOPING STAGE OF MAINTENANCE DIALYSIS IN TRANSYLVANIA - EARLY DEVELOPMENT OF PERIARTICULAR CALCIFICATIONS AND BETA-2-MICROGLOBULIN AMYLOIDOSIS IN SPITE OF A RELATIVELY GOOD PREVENTION OF SECONDARY HYPERPARATHYROIDISM

Background. - Dialysis facilities have been introduced only recently i n Transylvania with many limitations, in particular a standard high ca lcium dialysate, Al(OH)(3) as phosphate binder and pharmacological dos es of native vitamin D2, but neither CaCO3 nor 1 alpha hydroxylated vi tamin D. Rheumatological complaints and metastatic calcifications were frequent, leading to suspect either overt hyperparathyroidism, adynam ic bone disease or beta 2 microglobulin amyloidosis. Aims of the study . - Evaluate the prevalence of radiological osteitis fibrosa, amyloid osteoarthropathy and periarticular calcification and their link with P TH secretion, phophocalcic disorders, acidosis, bone turn over, alumin um and beta 2 microglobulin accumulation in the dialysis population of Sibiu (Transylvania). Methods. - The clinical and radiological rheuma tological data of the 49 uremic patients dialyzed in Sibiu since 1990 were reviewed as well as the monthly routine monitoring of their plasm a phosphocalcic parameters. Furthermore in July 1994, 36 of them had a n X rays of the hands for evaluation of subperiosteal resorption of th e phalanges, periarticular calcifications and carpal cysts as well as a determination of plasma concentrations of intact PTB (normal range: 10-55; optimal range: 100-200 pg/ml), osteocalcin, bone alkaline phosp hatase, aluminum and 25 OR vitamin D. Results. - The prevalence of sub periostal resorption of the phalanges was 8 % and that of severe biolo gical hyperparathyroidism (PTH > 400 pg/ml) 22 %, whereas that of a re lative hypoparathyroidism (PTH < 100 pg/ml) was 31 %. Mean plasma conc entrations of calcium was 2.07 +/- 0.15; of phosphate 2.50 +/- 0.35; o f bicarbonate 15 +/- 2.0 mmol/l, of 25 ORD 30 +/- 20 ng/ml, of aluminu m 1.1 +/- 0.5 mu mol/l. Plasma PTH concentrations were negatively corr elated to dialysis duration, and to plasma concentrations of aluminum, calcium and 25 OH vitamin D but not to those of phosphate and bicarbo nate. Multivariate analysis showed however that only duration of dialy sis and plasma aluminum concentration were independently and negativel y correlated to plasma PTH concentrations. The prevalence of periartic ular calcifications (26 %) and of carpal cysts suggestive of beta 2 mi croglobulin amyloidosis (10 %) were relatively high considering the yo ung age of the population (42 years) and the short duration of dialysi s (2.6 Sears). Patients with calcifications comparatively to those wit hout calcifications were older, had longer duration on dialysis, highe r prevalence of carpal cysts and higher plasma beta 2 microglobulin co ncentrations, lower plasma PTH (98 versus 313 pg/ml) and higher plasma aluminum concentration (1.3 versus 0.8 mu mol/l). Patients with carpa l cysts comparatively to those without cyst were older, had a longer d uration on dialysis and a higher prevalence of periarticular calcifica tions. Conclusions. - a) In spite of no use of 1 alpha hydroxylated vi tamin D derivatives, and poor control of hyperphosphatemia and acidosi s, hyperparathyroidism declined with duration of dialysis due to the u se of a high dialysate calcium concentration, AI(OH)(3) as sole phosph ate binder and high supplement of native vitamin D. b) Considering the relative young age and short duration on dialysis, the prevalence of periarticular calcifications and carpal cysts were high, c) Calcificat ions were possibly favored by relative hypoparathyroidism and moderate aluminum overload. d) The association of periarticular calcifications and subchondrial cysts suggest a causal relationship.