Itching in Liver Disease

[Guest guest]

Itching in Liver Disease

By Nora V. Bergasa, M. D.

Itching secondary to liver diseases, including primary biliary

cirrhosis, primary sclerosing cholangitis, and hepatitis C, is a very

difficult symptom for patients to endure and for physicians to

manage. The reason why patients with liver disease itch is not known.

It has been thought that some substances accumulate in the blood as a

result of liver disease, causing itch.

Although the nature of the substance(s) that cause itch in liver

disease is not known, evidence has been accumulating over the past

several years to suggest that some substances that are found normally

in plasma known as endogenous opioids (e.g. enkephalins), contribute,

at least in part to the itch secondary to liver disease. It has been

proposed that these neurotransmitters cause itch by acting on special

areas of the brain. Other substances that also accumulate in the

blood in liver disease, including bile acids, may also play a role in

this type of itch. There is no strong evidence, however, to support

that bile acids cause this type of itch.

Traditionally, the way itch has been studied has been by measuring

the concentration of substances known to accumulate in the blood of

patients with liver disease who itch. This method, however, has not

advanced the understanding of what causes this type of itch.

In order to conduct scientific investigation, investigators have to

apply reliable methods that allow for the collection of information

that can be analyzed and interpreted in an objective way. The need

for the availability of good methods has been recognized for many

years by investigators in the field of itch. In this spirit, an

instrument was designed over ten years ago that allows for the

measurement of the human behavior that results from feeling the

sensation of itch: scratching. Several clinical trials that use this

method to record scratching have been conducted. These studies have

provided some insight into itching and scratching, including the

demonstration that some patients scratch with a 24-hour rhythm, known

as circadian rhythm. This finding has suggested further that the itch

secondary to liver disease is mediated in the brain.

At present there are several medications that are used for the

treatment of itch in liver disease. These medications include

cholestyramine, the antibiotic rifampicin, the opiate antagonists

naloxone and naltrexone, and the serotonin type-3 receptor

antagonist. These medications appear to decrease itching in many

patients, but there is no medication that works well for all the

patients. This reality underscores the need to continue to look for

other medications that may relief the itch secondary to liver

disease.