Yukiko Nozawa1, Hiroe Sato2, Ayako Wakamatsu1, Daisuke Kobayashi1, Takeshi Nakatsue1, Yoko Wada1, Takeshi Kuroda3, Junichiro James Kazama4, Yoshiki Suzuki3, Masaaki Nakano5, Ichiei Narita1. 1. Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-Dori, Chuoku, Niigata City 951-8510, Japan. 2. Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-Dori, Chuoku, Niigata City 951-8510, Japan; Health Administration Center, Niigata University, 2-8050 Ikarashi, Nishiku, Niigata City 950-2181, Japan. Electronic address: hiroes@med.niigata-u.ac.jp. 3. Health Administration Center, Niigata University, 2-8050 Ikarashi, Nishiku, Niigata City 950-2181, Japan. 4. Department of Nephrology and Hypertension, Fukushima Medical University, 1Hikariga-oka, Fukushima City 960-1295, Japan. 5. Department of Medical Technology, School of Health Sciences, Faculty of Medicine, Niigata University, 2-746 Asahimachi-Dori, Chuoku, Niigata City 951-8518, Japan.
Abstract
BACKGROUND: Patients with rheumatoid arthritis (RA) often have reduced muscle mass. Estimated glomerular filtration ratio using the serum cystatin C concentration (eGFRcys) is more accurate than eGFR using the serum creatinine (eGFRcreat) because cystatin C is not influenced by muscle mass, but glucocorticoid therapy may affect serum cystatin C concentration. METHODS: Fifty patients with RA were included in this study. Renal inulin clearance (Cin) was measured and compared with eGFRcreat, eGFRcys, or the mean of eGFRcreat and eGFRcys (eGFRavg). RESULTS: The mean creatine kinase (CK) concentration was low (36.8 ± 24.4 U/l).The eGFRcreat and eGFRcys regression lines were significantly different from y = x. The mean eGFRcreat value was significantly higher than Cin and that of eGFRcys was lower than Cin. The difference between eGFRcys and Cin was negatively correlated with daily PSL dose. The mean eGFRcys value of patients taking <10 mg PSL was not different from Cin and the eGFRcys regression line was not different from y = x. CONCLUSION: eGFRcys of patients taking a daily PSL dose ≥10 mg was inaccurate, while eGFRcys was underestimated. eGFRcys was more accurate than eGFRcreat or eGFRavg for patients taking a daily PSL dose of <10 mg.
BACKGROUND:Patients with rheumatoid arthritis (RA) often have reduced muscle mass. Estimated glomerular filtration ratio using the serum cystatin C concentration (eGFRcys) is more accurate than eGFR using the serum creatinine (eGFRcreat) because cystatin C is not influenced by muscle mass, but glucocorticoid therapy may affect serum cystatin C concentration. METHODS: Fifty patients with RA were included in this study. Renal inulin clearance (Cin) was measured and compared with eGFRcreat, eGFRcys, or the mean of eGFRcreat and eGFRcys (eGFRavg). RESULTS: The mean creatine kinase (CK) concentration was low (36.8 ± 24.4 U/l).The eGFRcreat and eGFRcys regression lines were significantly different from y = x. The mean eGFRcreat value was significantly higher than Cin and that of eGFRcys was lower than Cin. The difference between eGFRcys and Cin was negatively correlated with daily PSL dose. The mean eGFRcys value of patients taking <10 mg PSL was not different from Cin and the eGFRcys regression line was not different from y = x. CONCLUSION: eGFRcys of patients taking a daily PSL dose ≥10 mg was inaccurate, while eGFRcys was underestimated. eGFRcys was more accurate than eGFRcreat or eGFRavg for patients taking a daily PSL dose of <10 mg.