Plasma was analyzed for urea N in duplicate by using a commercial colorimetric kit (BioAssay Systems,Hayward, CA). The sample mean for pooled plasma PUN was 5.0 ± 0.2 mM and the intra- and interassay CV were 4.2% and 4.6%, respectively. The sample mean for IgA pools was 8.9 ± 0.6 mg/mL, and the intra- and interassay CV were 4.8% and 4.5%, respectively.