Estimation of glomerular filtration rate in normal sheep by the disappearance of iohexol from serum

The aim of the study was to establish reference values for glomerular filtration rate (GFR) in healthy sheep from the clearance of iohexol in serum. Fifteen healthy sheep were tested twice with 14 to 21 days between tests. No side-effects were observed after iohexol injections and all the sheep were clinically normal during and after the study. The mean clearance of iohexol estimated by the two-compartment method was 1.8 ml/min per kg (95% CI = 1.6-2.0) in the first trial and 1.7 ml/min per kg (1.5-1.9) in the second trial. The mean GFRiohexol estimated by a one-compartment method was 1.9 ml/min per kg (1.7-2.2) in the first trial and 1.8 ml/min per kg (1.6-2.0) in the second. The GFR values were similar to those reported for the inulin method. The results indicate that the iohexol method is valid for estimating GFR in sheep, and it is easier to perform than the inulin method.