A Comparison of Stable and 3H-Labelled Polyethylene Glycol 4000 as Non-Absorbable Water Phase Markers in the Human Ileum and Faeces

Abstract
Polyethylene glycol 4000 (PEG plus 3H-PEG) was used as volume indicator during ileal perfusion in man. Faeces, urine, ileal infusates, and aspirates were investigated. Turbidimetrical assay and liquid scintillation counting (in the faeces radioassay was done after conbustion) yielded similar estimates of water absorption and secretion. Tracer amounts of 3H were found in the urine, indicating a minimal absorption. The simplicity of 3H radioassay and the reliability of 3H-PEG as a non-absorbable water phase marker is emphasized.