GDF15 and primary biliary cholangitis: Serum GDF15 levels in patients with AIH (1994.3 ± 1258.0 pg/dL) were higher than those in patients with HB (953.2 ± 871.4 pg/dL) or PBC (643.9 ± 247.0 pg/dL) and healthy controls (475.3 ± 145.3 pg/dL) (p < 0.0001) (Fig. 1A).