Korean Journal of Nephrology 1987;6(2):247-262.

정상 신기능을 가진 신증후군 쥐에서의 칼슘대사 및 대사성 골변화

정해일

Abstract

Derangement of calcium metabolism in patients with nephrotic syndrome has long been recognized even at normal status of renal function. Hypocalcemia, hypocal- ciuria and low levels of circulating 2 5-hydroxyvitamin D, are constant features in these patients, while true' hypocalcemia (ionized calcium) and increased levels of circulationg parathyroid hormone (PTH) have been noted onlv in some of them. Still controversial are the data on circulating levels of 1,25-dihydroxyvitamin D, and on the frequency of bone lesions. 'Atost of these observations, however, were random and cross-sectional, therefore controlled, longitudinal studies are essential to end these controversies. How- ever, this kind of study is in fact difficult to perform in actual patients especially in children. Author provoked and maintained nephrotic syndrome in 2'2 Wistar rats with a series of intraperitoneal injec- tion of Puromycin aminonucleoside, and made a longitu- dinal observation about activity of the nephrotic syndrome, renal functional status, some aspects of cal- cium metabolism and accompanying metabolic bony structural changes according to the duration of the nephrotic syndrome. The data were compared with those in 20 control rats also, and the final results was as follows; 1) In those rats with Puromycin injection(s), active nephrotic syndrome developed and persisted throughout the experimental period with typical biochemical changes of increasing proteinuria, decreasing serum albumin and increasing serum cholesterol. The light microscopic findings of their kidney tissue showed no abnormality. 2) During the whole experimental period, renal func- tions were maintained normally in both nephrotic and control rats as measured by serum creatinine level. 3) With persistent and aggravating nephrotic syndrome, serum total calcium level showed significant- ly decreased value. And there was an increasing tenden- cy in serum PTH level. 4) Micromorphometric examination of undecalcified lumbar vertebral body sections revealed a gradual increase in osteoid tissue in proportion to the duration of active nephrotic syndrome, and the increase in osteoid tissue was inversely correlated with both the serum levels of albumin and total calcium. In 6 rats with about 40 days of persistent nephrotic syndrome, definite increase in osteoid tissue was observed in all cases and there were similar inverse correlations between the amount of osteoid tissue and both the serum levels of albumin and total calcium. In conclusion, increased osteoid tissue was a constant and progressive feature in rats with persistent nephrotic syndrome and normal renal function as well as well- known derangement in some aspects of calcium metabo- lism.