B-type (brain) natriuretic peptide and pruritus in hemodialysis patients

Abstract

Yoshio Shimizu, Ayano Sonoda, Chieko Nogi, Yoko Ogushi, Reo Kanda, Saori Yamaguchi, Nao Nohara, Tatsuya Aoki, Kaori Yamada, Junichiro Nakata, Hiroaki Io, Atsushi Kurusu, Chieko Hamada, Satoshi Horikoshi, Yasuhiko Tomino Division of Nephrology, Department of Internal Medicine, Juntendo University Faculty of Medicine, Tokyo, Japan Introduction and objective: While pruritus is a common complication in hemodialysis patients, the pathophysiological mechanisms remain obscure. Recently, B-type (brain) natriuretic peptide (BNP) has been defined as an itch-selective neuropeptide in pruriceptive neurons in mice, and higher serum levels of BNP are frequently observed in hemodialysis patients. The objective of the present study was to evaluate the role of serum BNP in pruritus in patients undergoing hemodialysis. Patients and methods: The current cross-sectional study was performed on 43 patients undergoing maintenance hemodialysis. A visual analog scale (VAS) measuring the general severity of pruritus (values from 0 to 10, with higher values indicating more severe pruritus) in daytime and at night was self-reported by patients. Each patient's background and laboratory tests, including serum BNP in the post-hemodialysis period, were collected. The correlation between VAS and clinical parameters was evaluated. Results: Both daytime and nighttime VAS scores in diabetic patients were significantly less than those in nondiabetic patients. Multiple regression analysis revealed that pruritus in daytime was worsened by serum BNP (β=2.0, t=2.4, P=0.03), calcium (β=4.4, t=5.2, P<0.0001), and β2-microglobulin (β=2.0, t=3.0, P=0.007), while it was eased by age (β=–2.2, t=-3.2, P=0.0004). Nocturnal pruritus was severe in nondiabetic patients (β=1.7, t=3.8, P=0.0005) and weakened by the total iron binding capacity (β=–2.9, t=–3.1, P=0.004). Conclusion: It is suggested that a higher level of serum BNP increases the pruritus of hemodialysis patients in daytime and that diabetic patients are less sensitive to itch, especially at nighttime. Keywords: B-type brain natriuretic peptide, pruritus, hemodialysis, visual analog scale, itch-selective neuropeptide, pruriceptive neurons, cerebrospinal fluid