More than half of all patients undergoing dialysis complain of pruritus, and the mechanism isn’t really very well understood. Some studies have found no significant difference in serum levels of creatinine, BUN, calcium, phosphorus, alkaline phosphatase, PTH, and hematocrit in patients with pruritus vs without, but the general recommendation is to keep phosphorus and PTH under good control. One study did find a significant difference in the frequency of neuropathy in patients with pruritus, and another found an association with hemoglobin A1c.
Trials investigating treatment options have not yielded a cure, but treatments are out there, and include topical therapies such as emollients, capsaicin, gamma-linolenic acid, and tacrolimus, systemic therapies such as activated charcoal, gabapentin, pentoxyfilline, and thalidomide, and physical therapies like UV phototherapy, electroacupuncture, and renal transplantation. First and foremost, management involves ensuring the patient is adequately dialyzed and their calcium/phosphorus and PTH levels are well controlled. A flow chart (I love flow charts) is found in this article.
In the patient with severe refractory itching, a diagnosis to consider is Kyrle’s disease, or perforating folliculitis. Kyrle’s disease is associated with diabetes and CKD/ESRD- one series found 9 cases in 200 dialysis patients, and is an odd disorder wherein keratin, collagen, and elastic fibers migrate transepidermally. The lesions are small papules that are flesh colored or slightly hyperpigmented. They slowly enlarge with time and each one contains a central, keratotic, slightly depressed core. This core contains a plug filled with keratin, parakeratotic scale, and basophilic debris. The epidermis around the core is thinned, and the plugs can contact the dermis and become inflamed. Treatment is difficult, but some success has been noted with tretinoin creams (though these should be used with caution in dialysis patients due to risk of high vitamin A levels), avoidance of trauma and scratching- ie wearing gloves, trimming fingernails, and transcutanous nerve stimulators. Large lesions can be excised, and phototherapy has been particularly successful for dialysis patients. Occasionally, patients are cured with renal transplantation. I had a patient recently who was severely affected by pruritus and had been treated for everything from scabies to psychiatric disease. We diagnosed her with Kyrle's disease after a skin biopsy, and although the therapies were not immediately effective in eliminating the itching, it was some relief to her to put a name to her symptoms.