Uremic pruritus: a review

Novel insight on GRP/GRPR axis in diseases

The gastrin-releasing peptide receptor (GRPR), a member of the G protein-coupled receptors (GPCRs), binds to ligands such as gastrin-releasing peptide (GRP) and plays a variety of biological roles. GRP/GRPR signalling is involved in the pathophysiological processes of many diseases, including inflammatory diseases, cardiovascular diseases, neurological diseases, and various cancers. In the immune system, the unique function of GRP/GRPR in neutrophil chemotaxis suggests that GRPR can be directly stimulated through GRP-mediated neutrophils to activate selective signalling pathways, such as PI3K, PKC, and MAPK, and participate in the occurrence and development of inflammation-related diseases. In the cardiovascular system, GRP increases intercellular adhesion molecule 1 (ICAM-1) and induces vascular cell adhesion molecule-1 (VCAM-1). GRP activates ERK1/2, MAPK, and AKT, leading to cardiovascular diseases, including myocardial infarction. Central nervous system signal transduction mediated by the GRP/GRPR axis plays a vital role in emotional responses, social interaction, and memory. The GRP/GRPR axis is elevated in various cancers, including lung, cervical, colorectal, renal cell, and head and neck squamous cell carcinomas. GRP is a mitogen in a variety of tumour cell lines. Its precursor, pro-gastrin-releasing peptide (ProGRP), may play an important role as an emerging tumour marker in early tumour diagnosis. GPCRs serve as therapeutic targets for drug development, but their function in each disease remains unclear, and their involvement in disease progression has not been well explored or summarised. This review lays out the above mentioned pathophysiological processes based on previous research conclusions. The GRP/GRPR axis may be a potential target for treating multiple diseases, and the study of this signalling axis is particularly important.

Chronic Kidney Disease-Associated Pruritus: A Review

BACKGROUND

Chronic kidney disease-associated pruritus (CKD-aP), also known as uraemic pruritus, is a disabling symptom for patients and a challenging condition for clinicians. Despite being common amongst end-stage kidney disease (ESKD) patients, it remains underestimated and underdiagnosed. The exact pathogenesis remains largely elusive, which hampers the synthesis of a definite treatment approach.

SUMMARY

Chronic pruritus (lasting 6 weeks or more in duration) is a common and potentially disabling symptom in patients with advanced CKD. A unified hypothesis of pathogenesis has not yet been concluded. Studies have shown changes in the immunochemical milieu of the skin in patients with CKD-aP with several inciting stimuli identified. However, other unrecognized factors are likely to be involved. This article will review the current observations and understanding of the postulated pathogenesis of CKD-aP, as well as the evidence for current management strategies. Key Messages: CKD-aP is a common and troubling symptom amongst ESKD patients that is associated with decreased quality of life and poor prognosis. Its exact pathogenesis, at the time of writing, is not well-understood. A stepwise approach is recommended for management. Systematic reviews show the largest body of evidence was found for the effectiveness of gabapentin. Comparison is needed between newly emerging pharmacological agents such as kappa-opioid receptor agonists and more established agents, such as the gabapentinoids. Finally, renal transplantation should be considered in severe and refractory cases who are suitable transplant candidates as it has shown an excellent outcome in most cases.

Pruritus in Continuous Ambulatory Peritoneal Dialysis and Hemodialysis Patients

To study the prevalence and pathogenesis of uremic pruritus, CAPD and HD patients were asked to complete a questionnaire. The replies were quantitated based on numerical scales, and the results were compared with various hematological and biochemical parameters, underlying disease, and duration of dialysis. There were 113 CAPD patients (63 males and 50 females), mean age 60 (range 20–84) years, average time on CAPD 20 (range 1–163) months and 76 HD patients (44 males and 32 females) mean age 57 (range 23–81) years, mean time on HD 44 (range 2–242) months. Replies to questions were evaluated and graded by the same Investigator who did not know the patients.

Pruritus was present in 70 (62%) CAPD patients (64% in females and 600/0 in males p=NS) and in 41 (54%) HD patients (69% in females and 43% in males, p=0.025). Before starting dialysis pruritus was present in 30% CAPD patients and 28% HD patients. Pruritus was graded as mild, moderate and severe; the distribution was 58.6%, 34.3%, and 7.1% (CAPD) and 43.90/0, 41.5%, and 14.6% (HD), respectively. Dry skin was reported by 73% CAPD patients and 72% HD patients.

This xerodermia was correlated with the severity of pruritus and was also present In 65% CAPD and 48.5% HD patients without pruritus. Patients with pruritus were older than those without pruritus both for CAPD (63 vs 54 years, p=0.004) and HD (61 vs 51 years, p=0.003). A significant correlation was observed only between pruritus score and age for CAPD patients. There were no other correlations between pruritus and the other parameters studied.

We conclude that pruritus Is a frequent symptom In dialysis patients, but It Is severe only In a small proportion. Its prevalence, as also that of dry skin, Increases after start of dialysis and Is higher In females on HD.

Patients with pruritus are older, and the severity of pruritus correlates with age in the CAPD patients. Presence of dry skin correlates with severity of pruritus, and Its prevalence Is high even among patients without pruritus.

Prevalence and characteristics of pruritus in patients treated with different dialysis modalities

Introduction: Uremic pruritus is a common symptom in patients with end-stage renal disease (ESRD). Intense pruritus can lead to uncontrollable scratching, impaired sleep, anxiety, depression, therefore significantly lowering patient's life quality. Although the prevalence of uremic itch in patients on dialysis has declined over time, it is still present in peritoneal dialysis (PD) and hemodialysis (HD) patients. Aim: The aim of this study is to investigate the prevalence of pruritus in HD patients compared to PD patients, as well as possible differences in its presentation and correlation with demographic and clinical characteristics of the population. Material and methods: A total of 50 HD and 50 PD patients were included. Dialysis modality, patient demographic, clinical characteristics, and laboratory data were recorded. Data on the presence and duration of itching, skin dryness and scaling were obtained from a general itch questionnaire. The visual-analogue scale (VAS) and the 5-D itch scale were used for evaluation of pruritus. Results: Pruritus was present in 42% of PD patients and 24% of HD patients (p = 0.056), without statistically significant differences in the distribution and intensity of pruritus in patients on different dialysis modality. A significantly higher number of PD patients had dry (41 vs 31; p = 0.026) and scaling skin (31 vs 15; p = 0.001). Patients with pruritus in PD had significantly higher levels of intact parathyroid hormone (iPTH) (386.57±302.29 pg/mL vs 159.25±163.52 pg/mL; p = 0.033) and AST (23.84±11.36 U/L vs 14.7±3.73 U/L; p=0,002), while having significantly lower levels of urea (18.78±7.60 mmol/L vs 23.65±4,31 mmol/L; p=0.028), creatinine (717.96 ± 229.50 mmol/L vs 940.06±207.57 mmol/L; p=0.009) and potassium (4.17 ± 0,63 mmol/L vs 5.80 ± 0.80 mmol/L; p = 0.000) in comparison to HD patients with pruritus. Conclusion: Pruritus is a common symptom among ESRD patients treated with dialysis. In our study, a higher prevalence of pruritus was observed in PD patients. Dry skin and higher levels of iPTH have been singled out as possible contributing factors to the occurrence of itch.

Pruritus Associated With Chronic Kidney Disease: A Comprehensive Literature Review

The prevalence of pruritus in chronic kidney disease (CKD) patients has varied over the years, and some studies suggest the prevalence may be coming down with more effective dialysis. Chronic kidney disease-associated pruritus (CKD-aP), previously called uremic pruritus, is a distressing symptom experienced by patients with mainly advanced chronic kidney disease. CKD-aP is associated with poor quality of life, depression, anxiety, sleep disturbance, and increased mortality. The incidence of CKD-aP is decreasing given improvements in dialysis treatments, but approximately 40% of patients with end-stage renal disease experience CKD-aP. While the pathogenesis of CKD-aP is not well understood, the interaction between non-myelinated C fibers and dermal mast cells plays an important role in precipitation and sensory stimulation. Other causes of CKD-aP include metabolic abnormalities such as abnormal serum calcium, parathyroid, and phosphate levels; an imbalance in opiate receptors is also an important factor. CKD-aP usually presents as large symmetric reddened areas of skin, often at night. Managing CKD-aP is a challenge. Research in this area is difficult because most studies are not comparable given their small group samples, study designs, and lack of standardized study measures. The most commonly used treatment is a combination of narrow-band ultraviolet B phototherapy and a μ-opioid receptor antagonist such as naltrexone.

An Observational Longitudinal Study Investigating the Effectiveness of 75 mg Pregabalin Post-Hemodialysis among Uremic Pruritus Patients

A prospective, observational, longitudinal study was conducted to assess the effectiveness of 75 mg pregabalin (PG) post-hemodialysis (pHD) for treatment-resistant uremic pruritus (UP). A total of forty-five patients completed the entire six week follow-up. At the baseline assessment, the majority of the patients were distressed by the UP frequency and intensity. Sleep (mean = 3.30 ± 1.1), leisure/social activities (mean = 2.90 ± 0.80) and distribution (mean = 2.92 ± 0.34) were the three domains that were primarily effected by the UP. Overall, further reduction in the 5D-itching scale (IS) was noted at day 42, which confirmed a sustained (B = -12.729, CI -13.257 to -12.201, p < 0.001) relief of pruritus severity among patients with treatment-resistant pruritus. Patients with a higher serum calcium level had a score difference of +1 from the other patients (B = 1.010, p = 0.061). There was a reduction of 12 points compared to the baseline 5D-IS for each patient on day 42 after using pregabalin 75 mg PD pHD for 42 days, which represented major relief. Among the demographic factors, only gender was significantly associated with the 5D-IS score.

Disturbed skin barrier in children with chronic kidney disease

BACKGROUND

There are limited data on skin lesions in children with end-stage renal failure. The aim of the study was an evaluation of the skin barrier in children with different stages of chronic kidney disease (CKD). The prevalence of xerosis, its severity, as well as its link selected demographic factors, were examined.

METHODS

The study included 103 children: 72 with CKD stages 3-5 (38 on conservative treatment and 34 on dialysis) and 31 patients with primary monosymptomatic nocturnal enuresis as a control group. Initially, the study subjects described the localisation and severity of dry skin by themselves. Next, clinical evaluation of xerosis, non-invasive corneometric assessment of epidermis moisturising and the measurement of transepidermal water loss were performed.

RESULTS

Most CKD children reported dry skin. The problem of xerosis was identified more frequently in patients on dialysis (67.6 %) than on conservative treatment (42.1 %) (p = 0.01). CKD patients divided according to skin dryness did not differ with regards to age, sex, initial kidney disease and CKD duration.

CONCLUSIONS

Disturbed skin barrier is an important concern of children with CKD, intensifying as the disease progresses. This symptom occurs on early stages of CKD and it should be taken into consideration in the CKD management.

Cutaneous abnormalities in patients with end stage renal failure on chronic hemodialysis. A study of 458 patients

BACKGROUND

Cutaneous manifestations occurring in patients with end stage renal failure on hemodialysis are polymorphic and diverse.

OBJECTIVE

The aim of our study was to assess the prevalence and characteristics of different cutaneous manifestations in patients on hemodialysis.

PATIENTS AND METHODS

We led a transverse investigation of all patients on hemodialysis in 12 haemodialysis centres of Sfax (Tunisia). We examined 458 patients (254 men and 204 women). The hemodialysis history ranged from 6 months to 24 years. A total of 394/458 (86%) patients had cutaneous abnormalities. These included pruritus (56.6% of patients), paleness (60.7%), xerosis (52.8%), hyperpigmentation or hypopigmentation (38.4%), venous dilation near the fistula (22.2%), eczema in the fistula area (14.8%), half-and-half nails (13.5%), onychodystrophy (6.1%), subungual hemorrhage (4.5%), leukonychia (4.5%), stomatitis (5.6%), xerostomia (3.2%), gingivitis (2.4%), uremic breath (2.1%), and skin calcificatins (0.4%). Nephrogenic fibrosing dermopathy was not detected in any of our patients.

CONCLUSIONS

Pruritus, paleness, dry skin as well as hyperpigmentation and hypopigmentation are the most frequent skin abnormalities observed in hemodialysis patients. The early recognition of some cutaneous conditions associated with end stage renal failure and hemodialysis may allow early therapeutic intervention and decrease morbidity.

Sericin cream reduces pruritus in hemodialysis patients: a randomized, double-blind, placebo-controlled experimental study

Background

Uremic pruritus (UP) is a significant complication in ESRD patients and substantially impairs their quality of life. UP is considered to be a skin manifestation of chronic inflammation. Because sericin can suppress the release of pro-inflammatory cytokines, the purpose of this study was to investigate the short-term safety and efficacy of sericin cream for treating UP in hemodialysis patients.

Methods

This study used a double-blind design to investigate the effects of random topical administration of sericin cream and cream base (placebo) on either the right or left extremities of hemodialysis patients for 6 weeks. Skin hydration, irritation and pigmentation were evaluated every 2 weeks using Skin Diagnostic SD27. The visual analog scale for itching was also evaluated every 2 weeks, and the Kidney Disease Quality of Life Short Form was performed on the day of each patient’s enrollment and after 6 weeks of treatment.

Results

Fifty dialysis patients were enrolled, 47 of which completed the study. The hydration of the skin of the patients’ extremities increased significantly after administration of sericin cream; significant differences were found between sericin treatment and control after 6 weeks of treatment (p = 0.041 for arms and p = 0.022 for legs, respectively). Moreover, a significant difference was also found in skin irritation between the two treatments (p = 0.013 for arms and p = 0.027 for legs, respectively). At the end of the study, the skin pigmentation level was significantly reduced on both the arms (p = 0.032) and legs (p = 0.021) of the sericin-treated side compared with the side treated with cream base. The mean itching score decreased significantly from moderate to severe at the time of enrollment to mild pruritus after 6 weeks of treatment (p = 0.002). A better quality of life was found in all domains tested although statistically significant differences before and after treatment was found only in the patients’ pain scores, the effect of kidney disease on daily life, sleep quality and symptoms or problems related to kidney disease.

Conclusions

We conclude that sericin cream has a high potential for reducing UP in hemodialysis patients.

The trial registration number of this study is ISRCTN16019033; its public title is “sericin cream reduces pruritus in hemodialysis patients”.

Effectiveness of Topical Chia Seed Oil on Pruritus of End-stage Renal Disease (ESRD) Patients and Healthy Volunteers

BACKGROUND

Several studies have been performed to evaluate the efficacy of dietary n-3 fatty acid for patients with renal dysfunction. While about 40% to 80% of patients with end-stage renal disease (ESRD) complain about pruritus and xerosis, there are few reports on the effects of topical n-3 fatty acid on these symptoms.

OBJECTIVE

In order to investigate the possible beneficial effects of topical n-3 fatty acid, oils extracted from chia (Salvia hispanica) seed were formulated into topical products, the effects of which were measured.

METHODS

Five healthy volunteers having xerotic pruritus symptoms and 5 patients with pruritus caused by either ESRD or diabetes were involved in this study. A topical formulation containing 4% chia seed oils were applied for an 8-week duration. Subjective itching symptoms were assessed on a 6-point scale, as were other skin functions, namely transepidermal water loss and skin capacitance.

RESULTS

After the 8 weeks of application, significant improvements in skin hydration, lichen simplex chronicus, and prurigo nodularis were observed in all patients. A similar improvement was also observed among healthy volunteers with xerotic pruritus. Improvement of epidermal permeability barrier function and skin hydration, represented by trans-epidermal water loss and skin capacitance, respectively, were also observed. No adverse effects were observed in all the tested patients and volunteers.

CONCLUSION

Chia seed oil can be used as an adjuvant moisturizing agent for pruritic skin, including that of ESRD patients.

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

The uremic pruritus is a very painful symptom suffered by chronic haemodialysis patients and is observed in 22 to 74% of the subjects. The causes of uremic pruritus have not yet been clarified. During the last 20 to 30 years it has been focused on altogether 5 different pathophysiological hypotheses: stimulating influences (e.g. calcium phosphate deposits in the epidermis), stimuli (e.g. secondary hyperparathyroidism), neuropathic injuries (e.g. disturbance of the cutaneous innervation in patients with uremic peripheral neuropathy), and central nervous changes (e.g. accumulation of endorphins in uremic patients which is associated with increasing pruritus), and immunologic conditions. The last mentioned immunological hypothesis has increasing importance, not at least based on the fact that the application of a topical calcineurin inhibitor (tacrolimus) improves the uremic pruritus. However, this fact could not be confirmed in a recent prospective placebo-controlled study from the USA. Only after kidney transplantation with a functioning transplant the uremic pruritus is stopped. That is why no causal therapy exists so far. Actually, the uremic pruritus has to be treated by topical and systemic means in a symptomatic and polypragmatic way only. Urea represents one of the most important "natural moisturizing factors" which are responsible for the hydration of the skin. It has been demonstrated that older patients have decreased urea levels within the stratum corneum of the epidermis, whereas in patients with terminal kidney insufficiency - despite dryness of the skin - as a paradox finding elevated levels of urea have been assessed in the stratum corneum. Because of this reason, the meaning of urea as part of the "natural moisturizing factors" system is not understood, until now. However, there are very promising results of clinical phase II studies showing a significant effect of topical application of 2.5% L-arginine hydrochlorid ointment - a semi-essential amino acid - on improvement of dryness and, in particular, on improvement of pruritus in haemodialysis patients.

An update on pruritus associated with CKD

The prevalence of chronic kidney disease (CKD) and end-stage renal disease is increasing worldwide. Despite improvements in dialysis methods, including the development of novel biocompatible membranes and ultrapure dialysate, CKD-associated pruritus remains a common and significant public health issue. Not only does this distressing symptom profoundly impact on quality of life and sleep, recent evidence showed that pruritus also was associated with poor patient outcome. Nonetheless, nephrologists and other health care professionals often fail to recognize and adequately address the pruritus associated with CKD. The pathophysiological mechanism of CKD-associated pruritus is poorly defined, and, as a result, the development of specific therapies has proved to be a challenge. The purpose of this review is to highlight the importance of this neglected topic by providing an overview of recent epidemiological studies, outcomes data, proposed pathophysiological mechanisms, and emerging treatment options.

Therapeutic effect of topical gamma-linolenic acid on refractory uremic pruritus

BACKGROUND

Pruritus is a bothersome symptom affecting up to 80% of dialysis patients. Lymphocyte and cytokine interaction has an important role in the pathogenesis of uremic pruritus. Gamma-linolenic acid (GLA) is associated with immune modulation of T lymphocytes and lymphokines. The aim of this study is to determine whether topical GLA can attenuate uremic pruritus.

METHODS

Seventeen dialysis patients with refractory uremic pruritus who passed the screening criteria entered a prospective, randomized, double-blind, placebo-controlled, crossover study. They stopped all antipruritic therapy at least 2 weeks before the study and were randomly assigned to treatment with either GLA 2.2% cream or placebo-based cream applied to the entire body after taking a bath once a day and to pruritic sites 3 times a day for 2 weeks, and then the reverse treatment after a 2-week washout period. Severity of pruritus was evaluated by using a traditional visual analogue scale (VAS) and a modified questionnaire method (pruritus score [PS]). Hemogram, aspartate and alanine aminotransferases, bilirubin, albumin, blood urea nitrogen, creatinine, calcium, phosphate, and intact parathyroid hormone were measured.

RESULTS

Sixteen patients completed the study; 1 patient was withdrawn because of an allergic skin reaction. There were no significant differences between groups except for sex distribution. Median VAS and PS values between groups did not differ significantly at baseline. There is a greater antipruritic effect of GLA based on evaluation with both the VAS and PS. There is persistence of a residual effect into the second treatment period after GLA treatment.

CONCLUSION

GLA-rich cream is better than placebo-based cream for alleviating uremic pruritus. It is a useful adjuvant in the management of refractory uremic pruritus.

An epidemiology study of patients with uremic pruritus

BACKGROUND

Pruritus is a common problem in continuous ambulatory peritoneal dialysis (CAPD) and haemodialysis patients. There are few studies on the clinical characteristics of uremic itch, the cause of which is still unknown.

OBJECTIVES

The aim of this study was to define the prevalence and clinical characteristics of pruritus in CAPD and haemodialysis patients.

METHODS

A questionnaire was used to evaluate pruritus in 52 CAPD and 289 haemodialysis patients in two dialysis units. The relationship of various factors and medical parameters to itch was examined.

RESULTS

Of the 341 patients, 177 (51.9%) had pruritus at the time of examination, 97 (28.4%) had pruritus in the past. Pruritus was present in 145 (50.2%) of the haemodialysis patients and 32 (61.5%) of the CAPD patients. Men, patients with liver disease, and patients with pruritus before starting dialysis treatment were more likely to have uremic pruritus.

CONCLUSIONS

This study showed us that uremic pruritus was observed more in men than women. The high prevalence of uremic pruritus in our study does not support the decrease of pruritus due to an improvement in the management of dialysis patients.

Etiology and prognostic significance of severe uremic pruritus in chronic hemodialysis patients

Although uremia is well known as the most common cause of pruritus, the mechanisms of pruritus in chronic hemodialysis patients remain unclear. The purpose was to characterize uremic pruritus in more detail and to investigate whether severe pruritus is a marker for poor prognosis. A total of 1773 adult hemodialysis patients were studied. A questionnaire was given to each patient to assess the intensity and frequency, as well as pruritus-related sleep disturbance. We analyzed the relationship between clinical and laboratory data and the severity of pruritus in hemodialysis patients and followed them for 24 months prospectively. In total, 453 patients had severe pruritus with a visual analogue scale (VAS) score more than or equal to 7.0. Among them, more than 70% complained of sleep disturbance, whereas the majority of patients with a VAS score of less than 7.0 had no sleep disturbance. Male gender, high levels of blood urea nitrogen, beta2-microglobulin (beta2MG), hypercalcemia, and hyperphosphatemia were identified as independent risk factors for the development of severe pruritus, whereas a low level of calcium and intact-parathyroid hormone were associated with reduced risk. During the follow-up, 171 (9.64%) patients died. The prognosis of patients with severe pruritus was significantly worse than the others. Moreover, severe pruritus was independently associated with death even after adjusting for other clinical factors including diabetes mellitus, age, beta2MG, and albumin. Severe uremic pruritus caused by multiple factors, not only affects the quality of life but may also be associated with poor outcome in chronic hemodialysis patients.

Hemodialysis-related pruritus and associated cutaneous manifestations

BACKGROUND

Uremic pruritus is one of the most common disabling problems in patients with chronic renal failure. Few studies have evaluated itching and cutaneous manifestations in hemodialysis-dependent patients.

OBJECTIVES

The aim of this prospective study was to identify the prevalence of pruritus and cutaneous changes affecting patients undergoing hemodialysis.

METHODS

The degree of itching in 70 patients treated at the Haemek Medical Center Hemodialysis Unit, in northern Israel, was scored according to presence and severity. We examined the relationship between the quality of dialysis and the frequency of pruritus, and identified concurrent cutaneous disorders.

RESULTS

Pruritus was a common problem in the study cohort and affected 74.3% of hemodialysis patients at some point. The main characteristics of pruritus were a general pattern in 65.7% and mild intensity in 78.3% of observed patients. Duration of hemodialysis varied between 3 months and 13 years. There was no correlation between occurrence of pruritus and demographic or medical parameters (sex, type of kidney disease, regular medications or duration of hemodialysis) of the patients. Higher dialysis efficacy, as expressed by dialyser clearance, volume distribution of area, dialysis duration (Kt/v), may reduce the prevalence of pruritus (P < 0.02). None of the blood and chemical values considered (hemoglobin, creatinine, urea, phosphorus, calcium, albumin, parathormone and alkaline phosphatase) revealed any statistically relevant differences between pruritus groups. The appearance of foot ulcers was different between diabetic and nondiabetic individuals undergoing hemodialysis (P < 0.001).

CONCLUSIONS

Pruritus is still a common problem in hemodialysis-dependent patients. The prevalence of xerosis and excoriations was high in patients undergoing replacement therapy. Efficient replacement hemodialysis may provide a clinical benefit.

Cromolyn sodium: A potential therapy for uremic pruritus?

Uremic pruritus occurs in up to 50% of patients undergoing chronic hemodialysis. The pathogenesis of this disabling condition is unknown but likely involves multiple pathways involving the peripheral and central nervous system as well as local chemical and inflammatory mediators. Therapy has involved modification of the dialysis procedure, topical medications such as emollients, physical treatments such as ultraviolet light, and several oral medications such as antihistamines, activated charcoal, and gabapentin. Unfortunately, most of these therapies have not been subjected to rigorous clinical trials and clinical success has been variable. Two patients with disabling uremic pruritus refractory to multiple interventions are reported, who showed significant improvement in pruritus severity as assessed by a visual analog scale when they were treated with the mast cell stabilizer cromolyn sodium. Cessation of cromolyn resulted in return of pruritus, which improved with rechallenge with the medication. Cromolyn sodium may offer an alternative therapy for patients with refractory uremic pruritus, and should be subjected to a randomized placebo-controlled trial.

Uremic pruritus: a review

Pruritus is a major disorder among the skin derangements in advanced renal failure. Its prevalence seems to be diminishing perhaps because of improvements in dialysis treatment. Recent information suggests that interactions between dermal mast cells and distal ends of nonmyelinated C fibers may be important in the precipitation and regulation of the sensory stimuli. The knowledge as to the control of pruritus transmission to cortex areas is still incomplete but endogenous opioid and opioid receptors may have a role in this regard. A recent classification was proposed for pruritus based on the level of its origin. Uremic pruritus, however, seems to be too complex to fit perfectly in any of the suggested modalities. Inflammation and malnutrition are recognized risk factors for cardiovascular death in end-stage renal disease patients, which may be related to the genesis of pruritus. Consistent with this concept, lower serum levels of albumin and higher serum levels of ferritin were found in pruritic patients when compared to nonpruritic ones. Newer treatments for this difficult clinical problem are being developed and tested.

[Dialysis associated skin changes]

Patients with end-stage renal disease often suffer from different dermatologic conditions. Reports indicate that 50-100% of patients with end-stage renal disease have at least one cutaneous disorder. The persisting chronic uremia is responsible for a variety of structural and functional skin changes. Dialysis or even renal transplantation leads to an improvement of some uremia associated skin disorders, others however can persist.

Acquired perforating dermatosis in patients with chronic renal failure and diabetes mellitus

Acquired perforating dermatosis (APD) is a skin disorder occurring in the patients with chronic renal failure (CRF), diabetes mellitus (DM) or both. The purpose of this study was to clarify the clinical and histopathological features of APD, and evaluate role of scratching in the pathogenesis of APD. Twelve patients with APD associated with CRF and DM were enrolled in the study. In six patients who required hemodialysis, the lesions appeared 2-5 yr (mean 3 yr) after the initiation of dialysis, 18-22 yr (mean 19.3 yr) after the occurrence of DM. The other patients who did not receive hemodialysis noted the lesions 4-17 yr (mean 9.5 yr) after the onset of DM. All patients had an eruption of generally pruritic keratotic papules and nodules, primarily on the extensor surface of the extremities and the trunk. The histologic features of our cases showed a crateriform invagination of the epidermis filled by a parakeratotic plug and basophilic cellular debris. The period of treatment for patients who suffered from severe (7 cases) or very severe (3 cases) on the pruritus intensity was longer than that of patients who had mild pruritus (2 cases). These data showed that scratching appear to play a critical part in the pathogenesis of APD.

Prevalence and characterization of uremic pruritus in patients undergoing hemodialysis: uremic pruritus is still a major problem for patients with end-stage renal disease

BACKGROUND

Pruritus is a common disabling problem in patients with advanced end-stage renal disease. Few studies have evaluated the clinical characteristics of uremic itch.

OBJECTIVES

The aim of this multicenter study was to provide a comprehensive description of the prevalence and clinical characteristics of pruritus affecting patients with end-stage renal disease who are undergoing hemodialysis.

METHODS

A detailed questionnaire recently developed was used to evaluate pruritus in 219 patients undergoing hemodialysis treatment in 3 dialysis units. We examined the relationship of the quality of dialysis and various factors and medical parameters to itch.

RESULTS

Pruritus was a common symptom in the study population. Approximately 66% of the patients had pruritus at some point, and 48% were affected by it at the time of the study. There was no correlation between the occurrence of pruritus and demographic or medical parameters (type of kidney disease, medical management, dialysis efficacy as expressed by Kt/V) of the patient. The data suggest that uremic pruritus tends to be prolonged, frequent, and intense, and it can impair the patient's quality of life including a negative effect on sleep and mood. Major factors found to exacerbate pruritus include rest, heat, dry skin, and sweat. Major factors found to reduce pruritus include activity, sleep, hot and cold shower, and cold. Treatment with angiotensin inhibitors seemed to be more common among those with uremia who had itch (P =.02) whereas furosemide was more commonly used among those who never itched (P =.002).

CONCLUSION

This study provides a detailed description of uremic pruritus with new data on its characteristics including affective and sensory dimensions and associated symptoms.

Acquired reactive perforating collagenosis in a nondiabetic hemodialysis patient: successful treatment with allopurinol

The authors present a case of acquired reactive perforating collagenosis developed in a nondiabetic hemodialysis patient, who was treated successfully with allopurinol. Treatment of acquired reactive perforating collagenosis is difficult and often ineffective. The patient had been unresponsive to conventional treatments, but the pruritus was controlled, and skin lesions subsequently resolved after the treatment with allopurinol. Possible mechanisms of allopurinol treatment for acquired reactive perforating collagenosis are discussed.

Treatment of pruritus associated with systemic disorders in the elderly: a review of the role of new therapies

Generalised pruritus is common in the elderly. Idiopathic 'senile pruritus' is a diagnosis of exclusion, and an underlying systemic disorder should be sought. Thyroid disease, haematological malignancy, iron deficiency, cholestasis or renal impairment may be responsible for pruritus. Rarely pruritus may occur after cerebral infarction or as a paraneoplastic phenomenon. The mechanisms of pruritus are poorly understood. In systemic disorders, correction of the underlying disorder alleviates itch. However, when this cannot be achieved, a symptomatic approach is required. Response to treatment varies enormously and an empirical approach is often required. Topical applications are available to soothe the skin and bandaging techniques may improve their efficacy. A number of more targeted treatments are available for renal and cholestatic pruritus. Novel therapies such as thalidomide, opioid antagonists, ondansetron and phototherapy with ultraviolet (UV)-B radiation are now being used. Treatment of pruritus needs to be individualised, and the elderly present a particular challenge. Adequate delivery of simple emollients may be impossible because of physical impairment The elderly are more vulnerable to the adverse effects of treatments, comorbidities may alter the pharmacokinetics of drug metabolism and polypharmacy increases the likelihood of adverse drug interactions. Cognitive impairment can lead to poor compliance with treatment. The patient's general health, the severity of symptoms and the adverse effects of treatment all need to be considered. Most treatments are of benefit only to some patients; others derive only marginal improvement. Many of the newer treatments are unlicensed for pruritus and should preferably be administered under specialist supervision. We review the literature concerning the treatment of itch associated with systemic diseases, with particular emphasis on issues relevant to the elderly. Pruritus is a difficult symptom to treat. However, it is hoped that research into the mechanisms underlying the pruritus of systemic disease will allow a better understanding so that we should be able to look forward to more specific and effective therapies in the future.

Uremic pruritus: a clinical study of maintenance hemodialysis patients

Uremic pruritus is one of the most bothersome symptoms in patients with chronic renal failure. Its pathogenesis remains unclear. The aim of this study was to evaluate the frequency of uremic pruritus in hemodialysis patients and to correlate its presence and intensity with several clinical parameters. One hundred thirty patients on maintenance hemodialysis were included into the study. The intensity of pruritus was assessed by two methods: visual analog scale and specially adapted questionnaire scoring method. A significantly positive correlation (p < 0.00001) was demonstrated between the two methods for evaluating pruritus. Uremic pruritus was found in 40.8% of patients. An additional 36.1% of patients reported pruritus to have been present in the past during the renal disease period. Itching was generalized in 19% of patients; the remaining subjects suffered from scattered pruritus (50%) or pruritus in a single location (31%). A significant positive relationship (p < 0.02) was demonstrated between the total score of pruritus and duration of the hemodialysis period. Severity of pruritus and sleep disturbance caused by itching also significantly correlated (p < 0.05) with the duration of hemodialysis. Patients hemodialysed on polysulphone membranes more commonly suffered from pruritus than those on hemophane (p < 0.04) or cuprophane (p < 0.03) dialysis membranes. A marked relationship was demonstrated between the intensity of xerosis and prevalence of pruritus. Significantly more patients with very rough skin had pruritus compared to those with rough skin (p < 0.05) and those with slightly dry skin (p < 0.02). Itching was more common in female patients (p < 0.04), but patient age, underlying renal disease and erythropoietin intake did not correlate with the incidence or intensity of pruritus.

Is pruritus in chronic uremic patients related to peripheral somatic and autonomic neuropathy? Study by R-R interval variation test (RRIV) and by sympathetic skin response (SSR)

The problem of pruritus in uremic dialysed patients remains unsolved. The etiology of pruritus has not been precisely explained, and sometimes no efficient treatment is available. The aim of this study was to analyse the relationship between somatic neuropathy and pruritus as well as the relationship between pruritus and dysautonomia. Fifty-one patients with end-stage renal failure underwent basic neurological examination, nerve conduction velocity studies, and pruritus assessment by means of a questionnaire. Two tests were used to assess the autonomic nervous system, namely the R-R interval variation test in basal and profound breath conditions (RRIV) and the sympathetic skin response (SSR). Pruritus was found in 63% patients of the sample. Most of them had clinical symptoms and signs of peripheral sensorimotor neuropathy and dysautonomia. About 59% of uremic patients revealed abnormally reduced RRIV. About 45% of patients had abnormal (delayed or absent) SSR. The pruritus in uremic patients occurred significantly more frequently (P < 0.01) in patients with paresthesia. A nonsignificant but sizeable trend towards a relationship of pruritus with hypohidrosis and pathological SSR results was also observed. There was no relationship between the pruritus presence and RRIV results. According to our results the activity of the nervous system might play an important role in the mechanism of uremic pruritus, but paradoxically this latter appeared more tightly related to somatic neuropathy than to autonomic dysfunction. Our results also suggest that SSR may become a useful technique for the assessment of autonomic dysfunction in uremic patients.

Cutaneous manifestations of end-stage renal disease

Examination of the skin and nails can reveal many abnormalities in patients with end-stage renal disease that precede or follow initiation of dialysis treatment or kidney transplantation. This article focuses on specific and nonspecific cutaneous signs of end-stage renal disease, reviewing both banal and life-threatening conditions, including pruritus, perforating disorders, calcifying disorders, and bullous dermatoses. The pathogenesis, clinical findings, histologic findings, differential diagnosis, and treatment of these diseases are discussed. Cutaneous manifestations unique to kidney transplantation will not be covered. (J Am Acad Dermatol 2000;43:975-86.)

Ondansetron therapy for uremic pruritus in hemodialysis patients

Pruritus is a distressing symptom affecting up to 90% of dialysis patients. Conventional treatment with antihistamines is often ineffective and may have unacceptable side effects. Serotonin (5-hydroxytryptamine type 3 [5-HT(3)]) is known to enhance pain perception and pruritic symptoms through receptors on sensory nerve endings. Antagonism of 5-HT(3) receptors may be of use in treating uremic pruritus. We randomly assigned 16 hemodialysis patients with persistent pruritus to treatment with the 5-HT(3)-receptor antagonist, ondansetron (8 mg), or placebo three times daily for 2 weeks each in a prospective, placebo-controlled, double-blind crossover study. Patients scored their intensity of pruritus daily on a 0-to-10 visual analogue scale (0 = no pruritus, 10 = maximal pruritus), and daily use of antihistamines as escape medication was recorded. The median daily pruritus score did not change significantly during active or placebo treatment (preondansetron, 5. 3; interquartile range [IQR], 3.4 to 6.3; during ondansetron, 3.9; IQR, 2.7 to 5.0; P = not significant; preplacebo, 3.7; IQR, 3.0 to 4. 6; during placebo, 3.6; IQR, 2.4 to 4.8; P = not significant). The median daily percentage of escape medication use decreased from 21% (IQR, 9 to 61) to 9% (IQR, 0 to 33) with ondansetron (P = not significant) and from 53% (IQR, 0 to 88) to 5% (IQR, 0 to 31) with placebo (P = not significant). There was no difference in predialysis biochemistry test results or dialysis efficacy during treatment phases. Ondansetron does not improve pruritus in hemodialysis patients. Use of antihistamines decreased with both ondansetron and placebo.

A study on pruritus after parathyroidectomy for secondary hyperparathyroidism

BACKGROUND

The effective therapy for uremic pruritus remains a clinical challenge, and the factors affecting the pruritus before and after parathyroidectomy have not been defined.

STUDY DESIGN

Thirty-seven patients were operated on for secondary hyperparathyroidism. Their ages ranged from 14 to 73 years, and the duration of dialysis from 12 to as long as 168 months. Indications for surgery were skin itch in 22 patients and other reasons in 15 patients. Serum levels of calcium, phosphorus, intact PTH (i-PTH), and alkaline phosphatase were checked at two different intervals-before surgery and 1 week after operation. Immunohistochemical stain of mast cells, antihuman macrophage (CD68), antihuman dendritic reticulum cell (CD35), and i-PTH (IHPTH) were performed on skin specimens. Skin samples were prepared into tissue homogenates and analyzed for concentrations of interleukin-2 (II-2) and tumor necrosis factor-alpha (TNF-alpha). II-2 and TNF-alpha were measured by sandwich enzyme-linked immunosorbent assay. The extent of pruritus was evaluated on a visual analog scale (VAS) ranging from 0 to 10 and a behavior rating scale (BRS) ranging from 0 to 5, at a preoperative stage and 1 week after operation.

RESULTS

Serum levels of calcium, phosphorus, the product of calcium and phosphorous (Ca x P), alkaline phosphatase, and i-PTH changed significantly after parathyroidectomy. The VAS decreased from 5.4 +/- 3.2 to 1.8 +/- 1.5 (p < 0.001). Significant improvement of BRS was achieved 1 week after surgery (p < 0.001), and in the followup period. Before surgery, there was no correlation between serum levels of calcium, phosphorus, Ca x P, alkaline phosphatase, i-PTH, number of mast cells, CD68, CD35, and IHPTH, and the scale of itch estimated with either VAS or BRS. The tissue levels of Il-2 and TNF-alpha were not detectable in any of them. We noted that high levels of phosphorus and Ca x P affected the postoperative extent of pruritus. But a linear regression test showed Ca x P was the only factor affecting postoperative itch.

CONCLUSIONS

Pruritus in patients with secondary hyperparathyroidism can be reduced by parathyroidectomy. Apparently, high-level Ca x P is the only factor that seems to affect the postoperative extent of pruritus.

Pruritus in children

Pruritus is the most common of all dermatological complaints. Although pruritus is usually due to a primary skin disease, it may be a manifestation of a systemic illness. The majority of causes can be diagnosed from the history and physical examination. Laboratory investigations are usually not necessary. Treatment should be directed at the underlying cause whenever possible.

Essential fatty acid deficiency in renal failure: can supplements really help?

Abnormal fatty acid metabolism may contribute to clinical problems such as itching, abnormal perspiration, susceptibility to infection, delayed wound healing, anemia, and increased hemolysis, as seen in patients with chronic renal failure. A double-blind study of patients on hemodialysis who received either fish oil, olive oil, or safflower oil documented that patients may have increased levels of the proinflammatory prostaglandin PGE2 and that fish oil intervention may decrease these levels, change the fatty acid profile, improve hematocrit levels, and improve patient perception of symptoms of pruritus.

Acquired perforating dermatosis in a British dialysis population

A perforating disorder of the skin developing in association with chronic renal failure and often also diabetes, acquired perforating dermatosis (APD), affects up to 10% of patients receiving maintenance haemodialysis in North America. The prevalence of this condition in British dialysis patients has not yet been ascertained. We have undertaken a skin survey of our dialysis population (n = 80) to determine the prevalence and clinical presentation of APD, with subsequent assessment of disease management and outcome. Of 72 patients who participated in the survey, eight were found to have APD, seven of whom were also diabetic. Skin lesions had developed pre-dialysis in two patients, on commencement of dialysis in one, and after 1-3 years on dialysis in the remaining five. Patients typically presented with pruritic dome-shaped papules with central crusts arising on the trunk and extensor limb surfaces. Histological examination of biopsy specimens revealed two types of lesion, typified by either narrow or broad ulcer craters, each showing perforation of both collagen and elastic fibres. Topical/intradermal steroid or topical retinoid were effective therapies in certain of our patients. Clinical clearance was achieved after 3-12 months of treatment in five patients with improvement in the remaining two patients who received treatment. Of the four patients who were alive at 2-year review, three remained clear, while one patient continued to develop new lesions. We report an 11% prevalence of APD in our dialysis population, suggesting the disorder to be as prevalent in patients with chronic renal failure in Britain as in North America. An association of the disorder with long-standing diabetes was confirmed.

Randomised crossover trial of naltrexone in uraemic pruritus

BACKGROUND

Most dialysis patients develop pruritus, for which current treatment is unsatisfactory. Endogenous opioids may be involved in this pruritus. We studied the effect of the opioid antagonist naltrexone on the pruritus of haemodialysis patients.

METHODS

Naltrexone 50 mg per day by mouth was given to 15 haemodialysis patients with severe resistant pruritus in a randomised, double-blind, placebo-controlled crossover trial. The naltrexone or placebo periods lasted 7 days each with a 7-day washout between the two periods. Pruritus was assessed by the patients on a visual analogue scale from 0 (no pruritus) to 10 (maximum), and mean daily scores were calculated. Plasma histamine and beta-endorphin levels were measured, and spontaneous and stimulated basophil histamine-release were determined.

FINDINGS

The median pruritus scores at the end of the naltrexone treatment were 2.1 (interquartile range 1.5-2.15) for the naltrexone-placebo sequence and 1.0 (0.4-1.15) for the placebo-naltrexone sequence. The respective values before naltrexone was given were 9.9 (9.85-9.95) and 9.9 (9.3-10.0). Plasma beta-endorphin levels were normal and remained unchanged during the study. Plasma histamine levels were high (mean 2.32 [SD 0.11] ng/mL, normal < 1.0) and decreased after naltrexone (to 1.8 [0.09], p < 0.01). Basophils from haemodialysis patients stimulated by interleukin-3 plus IgE antibodies released high amounts of histamine. The increase was 78.3 (19.3)% compared with 26.6 (16.3)% for five normal controls (p < 0.01). Incubation of the basophils with naloxone, another opioid antagonist, prevented this effect.

INTERPRETATION

Our data suggest short-term efficacy with few side-effects for the amelioration of uraemic pruritus with naltrexone.

Sweat secretion, stratum corneum hydration, small nerve function and pruritus in patients with advanced chronic renal failure

Sweat secretion, stratum corneum hydration and small nerve fibre function were measured in 40 patients with advanced chronic renal failure (CRF), using pilocarpine iontophoresis, electrical capacitance and a thermal sensory analyser which measures the thresholds of warm and heat pain sensation. Correlations were sought between these parameters, and the presence and severity of pruritus and skin xerosis were compared with 45 healthy control subjects. The mean sweat secretion and stratum corneum hydration of CRF patients were significantly lower than in controls. Thirteen patients had pathological thresholds to warm sensation on the foot, and eight on the hand. None had pathological thresholds to heat-pain. The presence of pruritus did not correlate with any of the following: xerosis, stratum corneum hydration, sweat secretion or the results of thermal testing.