There was no difference in copeptin concentration between PD and HD patients (427 vs. 412 pg/mL, p = 1.0), while plasma copeptin was significantly lower in CKD5-ND patients compared to PD and HD patients (351 vs. 427 pg/mL, p = 0.02; and 351 vs. 412 pg/mL, p = 0.001, respectively). Here, AVP is linked to Huntington disease.