Iohexol clearance for assessment of glomerular filtration rate in diabetic pregnancy

Background: Plasma clearance of iohexol (Omnipaque(R)) is well suited for determination of glomerular filtration rate (GFR) during pregnancy. Objective: To settle guidelines for the use of iohexol clearance in diabetic pregnancy. Study design: Prospective comparative. Material and Methods: Iohexol (5 ml) was injected intravenously and plasma concentrations determined by high pressure liquid chromatography after 180-240 min in 44 diabetic pregnant women. Results: Iohexol clearance was normal in most cases of nephropathy or albuminuria. Iohexol clearance correlated negatively with blood pressure, S-Urate, and S-Creatinine. When S-Urate was <232 mu mol/l or S-Creatinine <70 mu mol/l; iohexol clearance was always normal (sensitivity = 1.0). When, in combination, S-Urate was >345 mu mol/l and S-Creatinine >70 mu mol/l, iohexol clearance was always subnormal (sensitivity = specificity = Kappa index = 1.0). Conclusions: In diabetic pregnancy, nephropathy or albuminuria cannot solely be used for selection of candidates for iohexol clearance determination. A S-Urate <230 mu mol/l (3.9 mg/dl) or S-Creatinine <70 mu mol/l (0.92 mg/dl) was reassuring for a normal GFR. We suggest iohexol clearance determinations in diabetic pregnancies when S-Urate is >350 mu mol/l (5.9 mg/dl) and/or S-Creatinine >70 mu mol/L.