The Use of 4-Aminobenzoic Acid as a Marker to Validate the Completeness of 24 H Urine Collections in Man

Publisher Website
Google Scholar
Abstract
At the present time there is no method whereby the completeness of 24 h urine collections can be accurately assessed when clinical studies are undertaken. The suitability of 4-aminobenzoic acid (PAB) given with meals as a marker for completeness of urine collections was therefore investigated. When a single dose of 80 mg of PAB was given to 4 volunteers 93% was recovered in the urine in 5 h. Eight volunteers living in a calorimeter, where complete urine collection could be guaranteed, were given various doses of PAB divided up throughout the day. In the urine, 88 .+-. 5% was excreted over a 24 h period. Urine excretion and oral dose were directly related. Thirty-three reliable free-living volunteers eating their normal diet took 80 mg of PAB with meals (240 mg/day). Mean urine recovery over the 24 h period was 223 .+-. 9 mg, or 93 .+-. 4% of the administered dose. The range in individual recovery from maximum to minimum was 15%, compared with 75% for creatinine excretion/kg fat-free mass. PAB is a safe marker of the completeness of 24 h urine collections. Any collection containing < 205 out of 240 mg (85%) of PAB, given as 80 mg with each of 3 meals, is probably incomplete.