title: Serum cystatin C levels to predict serum concentration of digoxin in Japanese patients.
abstract: 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.
authors.affiliation: Department of Hospital Pharmacy, School of Medicine, Kobe University, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakamura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ioroi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakaeda
authors.forename: Masanori
authors.initials: M
authors.lastname: Horinouchi
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Hayashi
authors.forename: Kensuke
authors.initials: K
authors.lastname: Saito
authors.forename: Mitsuro
authors.initials: M
authors.lastname: Kosaka
authors.forename: Noboru
authors.initials: N
authors.lastname: Okamura
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kadoyama
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kumagai
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Okumura