However, in previous studies that compared immunostaining skin sections treated with various common pruritogens (histamine, acetylcholine (Ach), etc.), uremic substances, and other substances causing itching (e.g., β-endorphin and endothelin-1), no significant difference was observed between patients with and without CKD-aP, even though the immunostaining epidermis sections were stained regardless of CKD-aP [1]. Here, EDN1 is linked to chronic kidney disease.