Erschienen in:
25.06.2019 | Original article
Increase of 1,25 dihydroxyvitamin D in sarcoidosis patients with renal dysfunction
verfasst von:
Naoya Toriu, Keiichi Sumida, Masahiko Oguro, Yoichi Oshima, Hiroki Mizuno, Eiko Hasegawa, Tatsuya Suwabe, Masahiro Kawada, Toshiharu Ueno, Noriko Hayami, Akinari Sekine, Rikako Hiramatsu, Masayuki Yamanouchi, Junichi Hoshino, Naoki Sawa, Kenmei Takaichi, Kenichi Ohashi, Keiichi Kinowaki, Takeshi Fujii, Ryosuke Date, Yoshifumi Ubara
Erschienen in:
Clinical and Experimental Nephrology
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Ausgabe 10/2019
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Abstract
Introduction
In sarcoidosis, renal involvement includes hypercalcemia-related nephrocalcinosis and granulomatous tubulointerstitial nephritis. Hypercalcemia is thought to be due to increased production of 1,25 dihydroxyvitamin D (1-25D), but 1-25D levels have not been evaluated in sarcoidosis patients with renal dysfunction.
Materials and Methods
We enrolled 9 sarcoidosis patients who underwent renal biopsy, and compared the serum 1-25D concentration and eGFR with those in 428 non-sarcoidosis patients who had renal dysfunction (stage 2 or higher CKD with an estimated glomerular filtration rate < 90).
Results
Serum calcium and 1-25D levels were significantly higher in the sarcoidosis patients than in the non-sarcoidosis patients (p < 0.01 and p = 0.01, respectively). There was a positive correlation between 1-25D and eGFR in the patients without sarcoidosis (r = 0.693; p < 0.01). As the renal function of sarcoidosis patients was improved by steroid therapy, the serum 1-25D and adjusted serum calcium levels decreased to near the median values in non-sarcoidosis patients. On renal biopsy, CD68 staining was positive for tissue macrophages in all 8 patients who had tubulointerstitial nephritis (with or without typical granulomas), while Von Kossa staining showed calcification of tubules near or inside granulomas in 6 of these 8 patients.
Conclusion
While tissue macrophages promote development of tubulointerstitial nephritis and 1-25D overproduction in renal sarcoidosis, hypercalcemia secondary to elevation of 1-25D may be related to renal calcification and granuloma formation.