Have We Just Scratched the Surface? A Narrative Review of Uremic Pruritus in 2020

PURPOSE OF REVIEW: Uremic pruritus is a highly prevalent and debilitating symptom in patients with chronic kidney disease (CKD) and end-stage kidney disease (ESKD). The purpose of this review is to examine current evidence on the mechanisms and treatments of pruritus in CKD and highlight promising areas for future research. SOURCES OF INFORMATION: Published literature, including randomized controlled trials, cohort studies, case reports, and review articles, was searched for evidence pertaining to the pathophysiology and treatment of uremic pruritus. METHODS: A comprehensive narrative review was conducted to explore the molecular mechanisms underlying uremic pruritus, as well as the evidence (or lack thereof) supporting pharmacological and nonpharmacological treatments for uremic pruritus. The potential role of patient sex in the pathophysiology and management of uremic pruritus is also discussed. KEY FINDINGS: The pathophysiology of uremic pruritus involves a complex interplay of uremic toxins, systemic inflammation, mast cell activation, and imbalance of opioid receptors. Classic treatment strategies for uremic pruritus include optimization of dialysis parameters, amelioration of CKD-related mineral and bone disease, topical emollients and analgesics, antihistamines, the anticonvulsant medications gabapentin and pregabalin, and ultraviolet light B (UV-B) phototherapy. Strong data to support many of these classical treatments for uremic pruritus are limited. Newly evolving treatment approaches for uremic pruritus include opioid receptor modulators, neurokinin-1 inhibitors, and cannabinoids. Further studies regarding their efficacy, pharmacodynamics, and safety in the CKD and ESKD population are needed before these agents are accepted into widespread use. Additional nonpharmacological strategies aimed at treating uremic pruritus include psychotherapy, acupuncture, omega-3 fatty acids, and exercise. Finally, sex differences may exist regarding uremic pruritus, but studies directly addressing sex-specific mechanisms of uremic pruritus remain absent. LIMITATIONS: High-quality evidence in the management of uremic pruritus remains lacking. Most recommendations are based on expert opinion or studies involving small numbers of patients. In addition, our understanding of the pathophysiological mechanisms behind uremic pruritus is incomplete and continues to evolve over time. IMPLICATIONS: Uremic pruritus is a common symptom which reduces quality of life in CKD and ESKD. The identification of novel targeted treatment approaches may ease the burden of uremic pruritus in the future.