CELLULAR PROLIFERATION AND SECRETION IN SECONDARY HYPERPARATHYROIDISMDURING RENAL-FAILURE

Secondary hyperparathyroidism is one of the severe complications of ch ronic renal failure. In this study, we investigated the cellular compo nents of parathyroid tissue, with measurements of various serum parath yroid hormone (PTH) types in the circulation, and evaluated their clin ical significance in hemodialysis patients. Thirty-eight patients who underwent both subtotal parathyroidectomy and autotransplantation in T okai University Hospital from 1979 to 1994 were divided into two group s. Group 1 (G-l) was not administered active-type vitamin D-3 (VD; 19 patients; 15 males and 4 females), and group 2 (G-2) was administered VD (19 patients; 10 males and 9 females). The parathyroid tissues whic h were obtained from G-l and G-2 patients were classified into three c lasses based on the size of the oxyphilic cell area (class I <25%, cla ss II 25-50% and class III >50%). Our results showed that the prolifer ation index of parathyroid tissues in the oxyphilic cell area was high er in G-2 than that in G-l. Immunohistochemically, MIB-1 staining was more intense than that in the chief cell area in G-2 patients. Moreove r, the proliferative index in the same specimen was also higher in the oxyphilic cell area than in the chief cell area. It was suggested tha t the oxyphilic cells proliferated independently. Furthermore, synthes is of PTH in the oxyphilic cell area was revealed immunohistochemicall y by the presence of PTH and was confirmed by positive staining of PTH mRNA in the oxyphilic cell area with in situ hybridization. HS(M-term inal)- and C-PTH levels in the serum were significantly higher in clas s III than in class I (p < 0.01). No significant difference of HS-and C-PTH levels between class II and class III was noted. Moreover, no si gnificant difference of intact-PTH levels was found in all three class es. From the above findings, it was suggested that proliferation of th e parathyroid tissues or secretory state of PTH in hemodialysis-mainta ined patients with secondary hyperparathyroidism, which was closely re lated to the proliferation of oxyphilic cells, can be more accurately reflected by HS-and C-PTH levels than by the intact-PTH level. Therefo re, it was suggested that HS-and C-PTH levels in the serum are importa nt indices for accurate evaluation of the pathology and suitable thera py of secondary hyperparathyroidism, as well as observation of the cli nical course.