Several uremic toxins may cause itching in hemodialysis patients, new research suggests.
Although its exact causes remain unclear, itching in hemodialysis patients has been associated with elevated levels of β2-microglobulin, calcium, phosphorus, or parathyroid hormone in the blood. Subsequently, improvements in hemodialysis therapy and pharmacological treatments have led to changes in the severity of itching and its associated factors in hemodialysis patients.
Uremic toxins 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. However, there have been no reports regarding their association with itching. in hemodialysis patients until now.
For this study, researchers from Niigata University Graduate School of Medical and Dental Sciences in Niigata, Japan investigated the details of itching and the factors associated with it, particularly focusing on PBUTs in hemodialysis patients.
They developed a “PBUT score” based on highly protein-bound uremic toxins (PBUT) that increase in the body with end-stage kidney disease. The PBUT score was associated with itching in hemodialysis patients.
Assessing itching using the 5D-itch scale, the study authors found that 38% of patients experienced itching, which was distributed throughout their backs and bodies (Figure 1).
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 (Figure 2). However, no association was found between itching and previously reported factors such as β2-microglobulin, calcium, phosphorus, and parathyroid hormone.
The frequency of itching was lower than in past reports possibly due 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, they conclude.
The research findings were published in Clinical Kidney Journal.