Uremic toxins associated with itching in hemodialysis patients

Individuals with advanced chronic kidney disease (CKD) rely on kidney replacement therapies like haemodialysis to manage their condition. However, these patients frequently endure various symptoms that diminish their quality of life and limit their activity.

Itching is a common symptom frequently observed in haemodialysis patients. Although its exact causes remain unclear, a survey conducted in Japan in 2000 found that itching was present in 73% of haemodialysis patients, and it was associated with elevated levels of β2-microglobulin, calcium, phosphorus, or parathyroid hormone in the blood.

Uremic toxins are a group of molecules whose concentrations increase in the blood due to kidney disease. Those molecules are associated with systemic diseases and prognosis in patients with end-stage kidney disease. Among them, molecules with high protein-bound properties, called PBUTs, such as indoxyl sulfate, are difficult to remove by dialysis therapy and have been reported to be associated with various pathologies.

Dr. Yamamoto et al. found several uremic toxins as one of the causes of itching in haemodialysis patients. For the study, the researchers investigated hemodialysis patients from dialysis facilities in Japan. Assessing itching using the 5D-itch scale, they found that 38% of patients experienced itching, distributed throughout their backs and bodies. Through principal component analysis of PBUTs including indoxyl sulfate, p-cresyl sulfate, indole acetic acid, phenyl sulfate, and hippuric acid, the PBUT score was generated. Patients with itching had higher PBUT scores compared to those without itching. However, no association was found between itching and previously reported factors such as β2-microglobulin, calcium, phosphorus, and parathyroid hormone.

The study’s findings demonstrated an association between PBUTs and itching in hemodialysis patients. “The decreased frequency of itching compared to past reports may be attributed to advancements in treatments such as those involving calcium and phosphorus. The improvement of the removal of PBUTs with dialysis treatment may be beneficial to treat itching in hemodialysis patients.” explained Dr. Yamamoto.

Reference: DOI: 10.1093/ckj/sfae007