Diapers May Distort Infant Metabolic Studies

Parents love disposable diapers but researchers may find them to be a pain in the behind. In a new study, biophysical chemist Michael Kennedy and colleagues at Miami University, in Ohio, demonstrate that diapers introduce contaminants into urine samples that may interfere with metabolic profiling of infant diseases (Anal. Chem., DOI: 10.1021/ac102572b).

Metabonomics, a growing field in clinical diagnostics, looks for unique metabolite signatures that indicate a bodily change, such as the onset of a disease. Kennedy and colleagues study necrotizing enterocolitis, a sometimes-fatal disease in which intestinal tissue dies. It occurs in about 10% of preterm, dangerously small babies. The investigators are searching urine for metabolites associated with NEC. A way to get samples without traumatizing the babies is to collect urine from wet diapers.

But Kennedy's team was concerned that the diapers leached chemicals. So they incubated eight disposable diaper brands with synthetic urine at 37 °C for three hours, a typical body temperature and duration between diaper changes. The researchers then analyzed the urine by either NMR spectroscopy or LC/MS, two dominant techniques in metabonomics. They found that most diapers introduced contaminants, such as polyethylene glycol, that could potentially interfere with the detection of some metabolites.

Kennedy recommends characterizing diapers before launching metabonomic studies of urine that involve large numbers of infants. That way, he says, "investigators can choose diaper brands that have either minimal or manageable contamination profiles."