title: A rapid urine creatinine assay by capillary zone electrophoresis.
abstract: Using capillary zone electrophoresis, the urine creatinine (uCr) assay was validated in extemporaneous diluted urine, both in healthy subjects and athletes, with the uCr concentration as a reference value to compare excretion rates of other metabolites in the same samples. The electrokinetic sample injection was carried out at 10 kV per 10 s; UV absorbance detection was at 254 nm. Using standard samples, the creatinine migration mean time in 100 mmol/L acetate buffer, pH 4.4, was 3.3+/-0.2 min; the repeatability for absolute migration mean time was 0.6% and peak height repeatability was 2.9%. The correlation coefficient of the standard curve was r = 0.999 and the detection limit was 23.1 micromol/L. Intra- and interassay coefficients of variation (CV) were 3.0 and 3.6%, respectively; recovery was 99+/-3% and linearity was r= 0.98. Normal urine samples were diluted 1:80 in run buffer. The present CE urine creatinine assay showed a good correlation with HPLC and with Jaffe methods (r = 0.98 and r = 0.97, respectively; p < 0.0001). The uCr in the morning urine samples of 34 healthy males (M), 38 healthy females (F), and 83 male athletes (A) was 10.4+/-6.1 mmol/L, 10.8+/-8.1 mmol/L and 13.2+/-6.5 mmol/L, respectively. The uCr difference (p < 0.02) between M and A and a correlation (p < 0.05) with age in A were observed.
authors.affiliation: Dipartimento Scienze Medico Diagnostiche e Terapie Speciali, Università degli Studi, Padova, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Gatti
authors.forename: V
authors.initials: V
authors.lastname: Lazzarotto
authors.forename: C B
authors.initials: CB
authors.lastname: De Palo
authors.forename: E
authors.initials: E
authors.lastname: Cappellin
authors.forename: P
authors.initials: P
authors.lastname: Spinella
authors.forename: E F
authors.initials: EF
authors.lastname: De Palo
mesh_terms: D001681:Biological Assay; D003404:Creatinine / Q000652:urine*; D019075:Electrophoresis, Capillary / Q000379:methods; D006801:Humans; D008297:Male; D013178:Sports Medicine
chemical_list: D003404:Creatinine