Serum cystatin C levels to predict serum concentration of digoxin in Japanese patients [Abstract]

Serum cystatin C levels to predict serum concentration of digoxin in Japanese patients

Tsutomu Nakamura¹, Takeshi Ioroi¹, Toshiyuki Sakaeda¹, Masanori Horinouchi¹, Nobuhide Hayashi², Kensuke Saito³, Mitsuro Kosaka³, Noboru Okamura⁴, Keiichi Kadoyama⁵, Shunichi Kumagai³, Katsuhiko Okumura¹ ⁴

1. Department of Hospital Pharmacy, School of Medicine, Kobe University, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
2. Clinical Pathology and Immunology, Department of Biomedical Informatics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
3. Dade Behring LIMITED, 1-3-17 Shinkawa, Chuo-ku, Tokyo 104-0033, Japan
4. Department of Clinical Evaluation of Pharmacotherapy, Kobe University Graduate School of Medicine, 1-5-6 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
5. Division of Molecular Regenerative Medicine, Department of Biochemistry and Molecular Biology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan

Cystatin C (Cys-C) has been recently paid great attention as a better endogenous marker of the glomerular filtration rate than creatinine (Cr). In this study, the usefulness of Cys-C was compared with Cr in terms of the estimation of the steady-state serum trough concentrations of digoxin in Japanese patients. Forty patients treated with digoxin and 56 healthy elderly subjects were participated in this study. The serum levels of Cys-C and Cr in the patients were higher than those in the healthy elderly subjects, but the increase of Cys-C was more predominant in the patients. Their levels were well-correlated for both of the healthy elderly subjects (r=0.691) and patients (r=0.774), but the serum concentrations of digoxin were better correlated with those of the reciprocal values of Cr (r=0.667) than those of Cys-C (r=0.383), presumably due to the fact that digoxin and Cr were excreted via both glomerular filtration and tubular secretion. Cys-C is useful for the substratification of the patients diagnosed to have normal renal function with Cr of < 1.3 mg/dL into those with normal and pseudo-normal renal function, resulting in the corresponding serum concentrations of digoxin.

Keywords: Cystatin C, Creatinine, Digoxin, Serum concentration, Heart failure, Renal clearance

How to cite this article:
Nakamura T, Ioroi T, Sakaeda T, Horinouchi M, Hayashi N, Saito K, Kosaka M, Okamura N, Kadoyama K, Kumagai S, Okumura K. Serum cystatin C levels to predict serum concentration of digoxin in Japanese patients. Int J Med Sci 2006; 3:92-96. Available from http://www.medsci.org/v03p0092.htm