Open AccessRisk of Overestimation of Kidney Function Using GFR ‐Estimating Equations in Patients with Low Inulin Clearance
Author(s) -
Nakata Junichiro,
Ohsawa Isao,
Onda Kisara,
Tanimoto Mitsuo,
Kusaba Gaku,
Takeda Yukihiko,
Kobayashi Noriyoshi,
Asanuma Katsuhiko,
Tanaka Yuichi,
Sato Michiko,
Inami Yuko,
Suzuki Hitoshi,
Suzuki Hiyori,
Masuda Atsumi,
aka Kanae,
Sasaki Yu,
Hisada Atsuko,
Hamada Chieko,
Horikoshi Satoshi,
Tomino Yasuhiko
Publication year - 2012
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.21513
Subject(s) - renal function , urology , inulin , cystatin c , creatinine , medicine , clearance , endocrinology , chemistry , biochemistry
Background Accurate estimation of the glomerular filtration rate ( GFR ) is very important in clinical practice. Although renal inulin clearance ( C in) is the gold standard for measuring GFR , the procedure for C in measurement is complicated. Use of GFR ‐estimating equations has been increasing recently due to their simplicity. The objectives of the present study are to analyze the correlation between C in and other GFR ‐estimating parameters and to investigate their clinical usefulness and limitation. Methods Seventy‐two Japanese patients were enrolled in this study. C in was measured by the continuous infusion method. Serum creatinine (s‐Cr), cystatin C , uric acid (UA), and hemoglobin (Hb) were measured. The J apanese formula of estimated GFR (e GFR ) was as follows: e GFR (ml/min/1.73m 2 ) = 194 × s‐Cr −1.094 × Age −0.287 × 0.739 (if female). The endogenous creatinine clearance test was also performed. Results Levels of C in were highly correlated with those of endogenous creatinine clearance ( C cr) ( R 2 = 0.7585) and e GFR ( R 2 = 0.5659). However, patients with lower C in showed unexpectedly elevated levels of endogenous C cr and e GFR . Moreover, the levels of e GFR tended to be unexpectedly increased in patients with low body surface area. Conclusion Although GFR ‐estimating equations are useful for estimating GFR accurately, they pose a risk of overestimation of kidney function in patients with decreased GFR or a poor physique. J. Clin. Lab. Anal. 26:248‐253, 2012. © 2012 Wiley Periodicals, Inc.