Fig. 2.

Immunoassay of soluble proteins. a Neutrophil gelatinase-associated lipocalin (NGAL) (b). Alpha-1 microglobulin (AMBP). c Retinol-binding globulin. All 3 were stable at room temperature, 4 °C, and −20 °C in urine (shown in this figure) without preservatives and also with toluene, thymol, and boric acid. None were stable with acetic acid, 6 N HCl, or 6 N HNO₃ (Additional file 2: Table S3). Median and interquartile ranges are shown