When the relationships among Th17‐related cytokines were investigated, we found that in HT patients, the plasma levels of IL‐17a were positively correlated with the levels of IL‐22, IL‐23, IL‐6, and IL‐10 (Figure 2A); additionally, IL‐22 was correlated with IL‐6, IL‐23, and IL‐10 (Figure 2B). This evidence concerns the gene IL22 and hematocrit.