Two by two hour creatinine clearance--repeatable and valid.
OBJECTIVE
The purpose of this study was to determine the repeatability and validity of 2 x 2 hour creatinine clearance, and the validity of creatinine clearances estimated by equations.


METHODS
In 30 patients two 2 x 2 h and two 24-h creatinine clearances were performed on consecutive days. In addition, creatinine clearances estimated by 4 different equations were calculated. Two by two hour creatinine clearance provided a measurement of GFR as valid as 24-h creatinine clearance.


RESULTS
We found, that 2 x 2 h creatinine clearance was well repeatable with a mean difference between 2 repeated measurements of 0.8 ml/min and low coefficients of repeatability of 14.5 ml/min. The validity of 2 x 2 h creatinine clearance, assessed by the mean difference between 2 x 2 and 24-h creatinine clearances, was 1.2 ml/min with tight 95% limits of agreement with a range from -8.1 to 10.5 ml/min. This high degree of repeatability and validity was present over the entire range of renal function (6-141 ml/min). As 2 x 2 h creatinine clearance is more simple and rapid than 24-h creatinine clearance, results are obtained on the same day and easy, but repeatable and valid day-to-day monitoring of renal function is possible. In addition, the two times two hour clearances allow for quality control. In contrast, estimated creatinine clearances show only poor validity.


CONCLUSIONS
Because of the high degree of repeatability and validity, 2 x 2 h creatinine clearance may replace 24-h creatinine clearance as the standard method to determine renal function in clinical practice.
Division of Nephrology, University Hospital, Essen, Germany.
S
S
Herget-Rosenthal
A
A
Kribben
F
F
Pietruck
B
B
Ross
T
T
Philipp
D000293:Adolescent; D000328:Adult; D000368:Aged; D003404:Creatinine / Q000378:metabolism*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008722:Methods; D008875:Middle Aged; D008962:Models, Theoretical; D015203:Reproducibility of Results
D003404:Creatinine