Optimal sampling times for OIH-clearance calculations using a two-compartment/two-sample method

Orthoiodohippurate (OIH) clearance data obtained with the two-compartment/two-sample method of Lear which uses varying sampling time combinations, were compared with those of the reference two-compartment/multi-sample method of Sapirstein. A total of 35 studies were performed in 33 adult patients. The OIH clearance values determined by the reference method ranged from 107 to 883 ml/min/1.73 m2, with a median of 406 ml/min/1.73 m2. It was ascertained that the precision of the Lear method is partially dependent upon the sampling time combination. The most reliable results with the Lear method in this patient population were obtained by taking a first sample at approximately 8 min p.i., and a second sample at 32 min p.i. or later.