[Pruritus and dryness of the skin in chronic kidney insufficiency and dialysis patients - a review]

Arsenic exposure and pruritus: Evidence from observational, interventional, and mendelian randomization studies

BACKGROUND

Pruritus is identified as an adverse drug reaction to arsenic trioxide, but the association of arsenic exposure with pruritus has not been investigated.

METHODS

A cross-sectional study was conducted in Shimen, China. A Mendelian randomization analysis was conducted to confirm the causal relationship between genetically predicted percentages of monomethylated arsenic (MMA%) and dimethylated arsenic (DMA%) in urine with chronic pruritus in UK Biobank. A case-control study was then conducted to determine the biomarker for pruritus. Arsenite-treated mice were used to confirm the biomarker, and von Frey test was used to induce scratching bouts. Last, a randomized, double-blind, placebo-controlled trial was conducted to test the efficacy of naloxone in arsenic-exposed patients with pruritus in Shimen.

RESULTS

Hair arsenic (μg/g) showed a dose-response relationship with the intensity of itch in 1079 participants, with odds ratios (OR) of 1.11 for moderate-to-severe itch (p = 0.012). The Mendelian randomization analysis confirmed the causal relationship, with ORs of 1.043 for MMA% (p = 0.029) and 0.904 for DMA% (p = 0.077) above versus under median. Serum β-endorphin was identified as a significant biomarker for the intensity of itch (p < 0.001). Consistently, treatment with arsenite upregulated the level of β-endorphin (p = 0.002) and induced scratching bouts (p < 0.001) in mice. The randomized controlled trial in 126 participants showed that treatment with sublingual naloxone significantly relieved the intensity of itch in arsenic-exposed participants in 2 weeks (β = -0.98, p = 0.04).

CONCLUSION

Arsenic exposure is associated with pruritus, and β-endorphin serves as a biomarker of pruritus. Naloxone relieves pruritus in patients with arseniasis.

Skin Lesions, Skin Care, and Characteristics of Pruritus in Patients Undergoing Haemodialysis

INTRODUCTION

Pruritus has been shown to be a common and burdensome complaint in the general population. In some diseases, there is an even higher rate and intensity of pruritus such as in chronic kidney diseases. In particular, patients requiring dialysis commonly suffer from pruritus with proportions between 22.0 and 90.0%. Few data on the characteristics and burden of such pruritus have been published. Therefore, the aim of this study was to investigate the extent and profiles of pruritus in such patients related to skin lesions and care.

METHODS

A non-interventional cross-sectional study in 14 centres for haemodialysis across Germany was conducted. The survey explored the prevalence, severity, and resulting burden of pruritus and skin lesions.

RESULTS

In total, 302 patients with uraemia (56.5% male, mean age 66.0 ± 14.4 years, mean duration of dialysis 3.9 ± 4.8 years) were included. Skin lesions appeared since start of dialysis in 50.0% of patients, with xerosis (94.7%) and desquamation (25.8%) being the most frequent and disturbing findings. Pruritus was reported by 60.9% of patients undergoing dialysis with a current mean numerical rating scale of 5.1 ± 2.4 occurring most frequently in the back, legs, and arms. About 89.0% of patients with xerosis and 69.0% with desquamation reported self-medication. However, only 40.0% and 28.0% sought medical help, respectively, indicating a remarkable lack of healthcare.

DISCUSSION

The current data suggest a more intensive focus on the skin symptoms and signs related to uraemia in the patients with dialysis and thus underline claims from a previous German large-scale study. Recommendations for early treatment and prevention of skin lesions in dialysis patients should be developed. Further research should be conducted focusing on recognizing subgroups of patients of particular vulnerability to pruritus and skin lesions, which may facilitate identifying patients at risk in an early moment. Moreover, a more specific tool for screening of skin lesions as well as pruritus may be useful since the existing instruments lack such specificity.

Clinical features and risk factors of pruritus in patients with chronic renal failure

Dermatological manifestations are common in systemic diseases, such as chronic kidney disease. The present study investigated the clinical features and possible influencing factors of pruritus in patients with chronic renal failure (CRF). A total of 382 inpatients were enrolled from the Department of Nephrology at The Second Affiliated Hospital of Chongqing Medical University. A total of 138 subjects were hemodialysis patients, 41 were peritoneal dialysis patients, and 203 were chronic renal failure patients. The patients' clinical performance was observed, and the data was recorded for analysis. The prevalence of pruritus in hemodialysis patients was greater than that in peritoneal dialysis patients. A total of 187 patients were accompanied by xerodermia and 109 patients had pruritus at the same time. With effective and regular dialysis, pruritus could be alleviated in 40% of patients. The intensity of pruritus in the enrolled patients ranged from mild itching to irritability during day and night periods. Moreover, pruritus was intermittent or persistent, and/or limited to generalized. Following treatment, 35% of patients had poor results. A significant difference was noted in the levels of serum urea nitrogen, creatinine, serum phosphorus, calcium × phosphorus, and parathyroid hormone (PTH) between patients with pruritus and non-pruritus. Xerodermia is a common skin manifestation in patients with chronic renal failure and is associated with the occurrence of pruritus. Local cold and heat stimulation can relieve pruritus to some extent, and adequate hemodialysis can also relieve itching.

Chronic pruritus in the elderly: pathophysiology, diagnosis and management

Chronic itch in the elderly is a common problem, with a significant impact on quality of life and sleep in elderly patients. Chronic itch may be attributable to several causes, including dry skin, immunosenescence and neural degeneration. Itch may also be caused by skin diseases, such as seborrhoeic dermatitis and stasis dermatitis; systemic conditions, such as end-stage renal disease and diabetes; and psychogenic conditions, such as depression and anxiety. The use of polypharmacy may also cause itch, with or without a rash. Specifically, thiazides and calcium channel blockers have been known to cause itch in elderly patients. Management should be tailored according to the underlying dermatological or systemic aetiology of itch. Topical treatment is the mainstay of therapy, providing special emphasis on skin hydration and barrier repair. In addition, topical and oral medications that target the nervous system and reduce neuronal hypersensitization, such as gabapentin and selective antidepressants, have a role in treating patients with severe chronic itch. Furthermore, management must account for changes in metabolism and pharmacokinetics of drugs in the aging population in order to prevent the occurrence of adverse effects.

Gabapentin versus pregabalin in improving sleep quality and depression in hemodialysis patients with peripheral neuropathy: a randomized prospective crossover trial

PURPOSE

In dialysis patients, painful peripheral neuropathy (PPN) is associated with sleep disturbance and mood disorders. Our goal was to compare the effects of gabapentin and pregabalin on improving sleep quality and depression among hemodialysis patients with PPN.

METHODS

Fifty hemodialysis patients with PPN were randomized into 2 groups, to receive gabapentin and pregabalin, respectively. After 6 weeks of treatment, patients underwent a 2-week washout period, followed by crossover and another 6 weeks of treatment. All patients underwent electromyography (EMG) at the outset and completed the modified Short Form of McGill Pain Questionnaire (SF-MPQ), the Beck Depression Inventory (BDI) and the Pittsburgh Sleep Quality (PSQI) assessment at baseline and at the end of the study. Forty out of 50 patients completed the 14-week study period.

RESULTS

Thirty-one out of 40 patients (77.5 %) had EMG-proven PPN. Both gabapentin and pregabalin significantly improved SF-MPQ, BDI and PSQI scores at the end of the study compared with pretreatment scores (p < 0.001). There was no significant difference between the two drugs in any studied parameter.

CONCLUSIONS

Our results showed for the first time a good and similar efficacy of both drugs on pain intensity, quality of sleep and depression in hemodialysis patients with PPN.