Since GDF-15 was high in male patients compared with female patients (P = 0.0008) and the positive correlation of GDF-15 with age was present (rs = 0.53, P <0.0001), a multivariate logistic regression analysis was adjusted by age and gender which still showed the tendency (parotid glands OR 4.10, 95% CI 0.99–21.8, P = 0.053; retroperitoneal fibrosis OR 2.53, 95% CI 0.77–8.87, P = 0.13). Here, GDF15 is linked to IgG4-related retroperitoneal fibrosis.