Uraemic pruritus

What is uraemic pruritus?

Uraemic pruritus is also called chronic kidney disease associated pruritus (CKD-associated pruritus). Uraemia refers to excessive urea in the blood, and occurs when both kidneys stop working (renal failure). Pruritus, or itch, is a common problem for patients with chronic renal failure or end stage renal disease. It affects about one-third of patients on dialysis and is more common with haemodialysis than continuous ambulatory peritoneal dialysis (CAPD).

Uraemic pruritus is not associated with sex, age, ethnicity, duration of dialysis, or cause of renal failure. Pruritus does not arise when uraemia is due to acute renal failure.

What are the signs and symptoms of uraemic pruritus?

Uraemic pruritus is characterised by daily bouts of itching that tend to worsen at night and may prevent sleep. The itch may be generalised or localised to one area, most often the back, abdomen, head and /or arms. In haemodialysis patients, the pruritus is lowest the day after dialysis and peaks 2 days afterwards.

The skin may appear normal or dry (xerosis), with few to numerous scratch marks and/or picked sores.

Uraemic pruritus (renal itch)

Uraemic pruritus (renal itch)

Pruritus

What are the complications of uraemic pruritus?

Scratching may lead to impetigo (skin infection), prurigo (papules) and chronic, lichenified dermatitis / eczema.

Uraemic pruritus can be very unpleasant; about half of affected individuals become agitated or depressed. Uraemic pruritus in haemodialysis patients is associated with a 17% increase in mortality.

What causes uraemic pruritus?

Uraemic pruritus is thought to be due to a combination of factors including:

• Dry skin
• Reduced sweating
• Abnormal metabolism of calcium and phosphorus / raised parathyroid hormone
• Accumulation of toxins
• Sprouting of new nerves
• Systemic inflammation
• Co-existing medical problems, particularly diabetes and liver disease.

Some patients have acquired perforating collagenosis.

What is the treatment of uraemic pruritus?

The first step in treatment is optimising dialysis efficacy. It is also important to attempt to reduce serum parathyroid hormone to normalise calcium/phosphorus.

Dry skin can be managed by using non-soap cleansers and applying emollients such as sorbolene cream or petrolatum several times daily.

Menthol and camphor may be added to an emollient to cool the skin and relieve the itch. Any localised itch may be reduced by frequent applications of topical capsaicin if tolerated.

UVB phototherapy is the mainstay of treatment for severe uraemic pruritus. Oral antihistamines and systemic steroids are generally not effective.

Other treatments that have been reported to help some individuals include:

• Gabapentin and pregabalin in small doses (eg, 100-300 mg gabapentin, three times weekly)
• Nalfurafine (opioid agonist)
• Activated charcoal
• Thalidomide
• Cholestyramine
• Ondansetron
• Dupilumab.

In 2019, in a Phase III clinical trial, an agonist of kappa opioid receptors, difelikefalin, was reported to relieve the itch in haemodialysis patients significantly better than placebo.

Kidney transplantation usually results in resolution of uraemic pruritus.