Evaluation of iohexol clearance used to estimate glomerular filtration rate in clinically normal foals.

The research is about a study that reveals iohexol clearance can be used to predict exogenous creatinine clearance and can be obtained from just two blood samples, taken after i.v. injection of the substance, from clinically normal foals.

Methodology

• The study was conducted on 10 healthy foals – 5 males and 5 females.
• The serum disposition of two substances, iohexol and exogenous creatinine, was simultaneously determined in each foal.
• A standard method was used to select a 3-compartment model of iohexol serum disposition.
• The clearance of iohexol calculated from the model was then compared with creatinine clearance.
• Separate limited-sample models were created with various combinations of sample times from the terminal slope of the plasma versus time profile for iohexol.
• Correction factors were determined for the limited-sample models, and iohexol clearance calculated via each method was then compared with exogenous creatinine clearance using method comparison techniques.

Results

• The average exogenous creatinine clearance was found to be 2.17 mL/min/kg.
• The disposition of iohexol was best described by the chosen 3-compartment open model.
• The mean clearance value for iohexol was 2.15 mL/min/kg, a value that was not significantly different from the mean creatinine clearance.
• Through this study, a method to predict serum iohexol clearance, based on a 2-sample protocol (3- and 4-hour samples), was developed.

Conclusions

• The study concludes that iohexol clearance can be used to predict exogenous creatinine clearance.
• The iohexol clearance can be determined from only 2 blood samples taken post i.v. injection of iohexol.
• The study acknowledges that appropriate correction factors need to be determined for adult horses and horses with an abnormal glomerular filtration rate.