Pruritus treatment will differ with liver and kidney disease.
SANTA BARBARA, CALIF. -- Solutions exist for patients with severe pruritus associated with liver or kidney disease, but they may not be the same as for patients with nonmetabolic causes of itch, according to Timothy G. Berger, M.D.
In the case of liver disease, one must go to the source: the brain, Dr. Berger said at the annual meeting of the California Society of Dermatology and Dermatologic Surgery.
"The thing that you were taught in medical school about an increase in bile acids in the skin [of patients with liver disease] and all that? That's all wrong," said Dr. Berger, professor of clinical dermatology at the University of California, San Francisco.
Researchers at the National Institutes of Health conducted a number of "wonderful studies" that proved patients with liver disease do not properly metabolize endogenous opiates, and that "itching may be a complication of that problem," he said.
"Pruritus in liver disease originates in the brain by increased neurotransmission mediated by endogenous opiates," he explained. These patients, in fact, can get opiate withdrawal symptoms even though they are not taking opiates.
The solution, then, is to block opiates in the brain.
If topical steroids, phototherapy, and other standard pruritus therapies fail to work, start patients with liver disease on very low dosages of naltrexone (50 mg/day) and titrate upward. During the first week, prescribe 100 mcg of clonidine to avoid opiate withdrawal syndrome, he advised.
Dr. Berger cautioned colleagues to be sure patients are not actually taking opiates during initiation of therapy. He described the case of a 102-year-old patient with liver disease and severe itching who failed to inform him of the fentanyl patches she wore for her osteoporotic pain. "She had opiate withdrawal syndrome and had to be hospitalized for 2 days," he said. "So be careful."
Other approaches used for liver disease-related pruritus include cholestyramine or its better-tolerated alternative, colestipol; rifampin; albumin dialysis; and, as a last resort, liver transplantation.
Severe pruritus in patients with renal disease is less well understood.
"As opposed to liver disease and itch, here we have significant disease and we have no due what the cause is," said Dr. Berger.
Treating xerosis, which may be profound in renal disease patients, and enhancing their dialysis regimen are good first steps.
Next, administer broadband--not narrow-band--UVB, which is more effective in renal disease-related pruritus.
Finally, prescribing a single, 200- to 300-mg dose of gabapentin (Neurontin) after each dialysis session has been shown to have dramatic effects.
"One pill and barn! The itching drops right off," he said.
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|Title Annotation:||Skin Disorders|
|Publication:||Family Practice News|
|Date:||Nov 15, 2005|
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