During the course of nephrotic syndrome daily urinary sodium concentration dropped to minimal values of 5 ± 1 μmol mg−1 creatinine and 6 ± 1 μmol mg−1 creatinine in Habp2+/+ and Habp2−/− mice, respectively, despite constant food and fluid intake (Fig. 4, b–c), urinary potassium excretion was not altered appreciably (Fig. 4, d). Here, HABP2 is linked to nephrotic syndrome.