[Correlation between four-hour creatinine clearance and 51Cr-EDTA test].
BACKGROUND
Creatinine clearance as a measure of glomerular filtration rate has several sources of error such as tubular creatinine secretion or faulty urine collections. On the other hand 51Cr-EDTA test is reliable and accurate, except in patients with edema, in whom the radioisotope equilibrium is retarded after injection.


OBJECTIVE
To validate a 4-hours creatinine clearance correlating it with 51Cr-EDTA test.


METHODS
In 59 non insulin dependent diabetic patients without diabetic nephropathy, glomerular filtration rate was measured using one 50 microCi injection of 51Cr-EDTA and collecting blood samples for radioactivity measurement at 10, 30, 120 and 240 min. Simultaneously, creatinine clearance was measured using a 4 hours urine collection.


RESULTS
The general correlation coefficient between both methods was 0.85 (p < 0.001). For glomerular filtration rates below 95 ml/min, the correlation coefficient was 0.8 (p < 0.001), for values between 95 and 127 ml/min, the correlation was 0.51 (p < 0.001) and for values over 127 ml/min the correlation was 0.8 (p < 0.001). The regression equation obtained was y = 1,2x + 13 where y was the glomerular filtration rate measured with 51Cr-EDTA and x the same value measured with creatinine clearance.


CONCLUSIONS
The four hours creatinine clearance is a reliable method to estimate glomerular filtration rate.
Peréz
E
E
Unidade de Nefrología, Hospital San Juan de Dios, Santiago de Chile.
Ugarte
C
C
Durruty
P
P
Soto
M C
MC
Ayca
V
V
Sotomayor
G
G
Soledad Barría
M
M
D002860:Chromium Radioisotopes / Q000378:metabolism; D003404:Creatinine / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000503:physiopathology*; D004492:Edetic Acid; D005919:Glomerular Filtration Rate; D006801:Humans; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013997:Time Factors
D002860:Chromium Radioisotopes; D004492:Edetic Acid; D003404:Creatinine
Correlación entre clearance de creatinina de 4 horas y la prueba de 51Cr-EDTA.