Fig. 1

a NEPTUNE spot urine sample processing: Sample 1: 4 × 2 mL cryovials whole unprocessed “raw” urine (SU). Sample 2: 4 × 2 mL samples with sodium azide additive (AS). Supernatant after low speed centrifugation is saved in cryovials with 20 μL 100 mM sodium azide (12 mL × 4). Sodium azide has anti-bacterial properties. Sample 3: 4 cryovials with proteinase inhibitor (PI). Sample 4: 2 sets of pellet from this are stored in RNAlater obtained by centrifugation at 1000 g × 12 min in a tabletop centrifuge (AP-E). Sample 5: 4 × 2 mL from the PI sample. 2 sets of pellet from this are stored in in RNAlater obtained by centrifugation at 1000 g x 12 min in a tabletop centrifuge (AQ-Q). All samples are stored on ice in transport and during collection. All samples are frozen as soon possible at −80 °C. Cryovial final volume stored is 1.6 mL urine. b NEPTUNE 24-h urine sample processing. One subaliquot 40 mL whole urine (inverted x 3) frozen at −80 °C immediately (U1). 1 subaliquot (40 mL) of whole urine with protease inhibitor (6 μL; Sigma P1860) (UQ1); 5 × 5 mL cryovials whole urine (U-24)