Collection and preservation of urinary proteins, using a fluff pulp diaper

Change is the most fundamental property of a biomarker. In contrast to the blood, which is under homeostatic controls, urine reflects changes in the body earlier and is more sensitive, thus making it a better biomarker source. Moreover, drawing blood from infants and toddlers is difficult and not tolerated well. For patients limited by language, communicating their chief complaint is difficult. Thus, monitoring biomarkers in urine can provide valuable clues for the diagnosis of diseases, especially pediatric diseases. Collecting urine from young children and some adult patients is more challenging than collecting it from healthy adults. Here, we propose a method that uses a fluff pulp diaper to collect urine. Urinary proteins are then eluted and adsorbed onto a piece of nitrocellulose membrane, which can be dried and stored in a vacuum bag. SDS-PAGE and LC-MS/MS analysis indicated that this method is reproducible, and similar proteins were identified as those obtained by an acetone precipitation method. With this simple and economical method, it is possible to collect and preserve urine samples from infants, toddlers, and patients with special needs, even for large-scale biomarker studies.