Primary Biliary Cirrhosis (cont.)
John M. Vierling, MD, FACP
John M. Vierling M.D. is Professor of Medicine and Surgery at the Baylor College of Medicine in Houston, Texas, where he also serves as Director of Baylor Liver Health and Chief of Hepatology. In addition, he is the Director of Advanced Liver Therapies, a center devoted to clinical research in hepatobiliary diseases at St. Luke's Episcopal Hospital. Dr. Vierling is board certified in internal medicine and gastroenterology and a Fellow of the American College of Physicians.
Leslie J. Schoenfield, MD, PhD
Dr. Schoenfield served as associate professor of medicine and consultant in gastroenterology on the faculty of the Mayo Clinic for seven years. He became a professor of medicine in residence at UCLA from 1972 to 1999 (now emeritus). He was the director of gastroenterology at Cedars-Sinai Medical Center in Los Angeles for 25 years, where he received the chief resident's teaching award, the president's award, and the pioneer of medicine award.
In this Article
- What is PBC?
- What is the scope of the problem?
- What is the cause of PBC?
- What are the symptoms and physical findings in PBC?
- What manifestations are specifically due to PBC itself?
- What are the manifestations of the complications of cirrhosis in PBC?
- What are the manifestations of diseases associated with PBC?
- What are risk factors for PBC?
- How is PBC diagnosed?
- What is the role of blood tests?
- What is the role of testing for antimitochondrial antibodies?
- What is the role of imaging tests?
- What is the role of liver biopsy?
- What are the criteria for a definitive diagnosis of PBC
- What is the course of natural progression in PBC?
- What are the sequential clinical phases of PBC?
- What is the role of mathematical models in predicting the outcome (prognosis) in PBC?
- What about pregnancy in PBC?
- Find a local Gastroenterologist in your town
What manifestations are specifically due to PBC itself?
The most common symptom of PBC is fatigue, which occurs in up to 70% of patients. The presence and severity of fatigue, however, does not correspond (correlate) with the severity of the liver disease. It should be noted that significant fatigue can be either the cause or the result of difficulty sleeping or depression.
Fatigue associated with inflammation of the liver is often characterized by normal energy during the initial half to two thirds of the day followed by a profound loss of energy that requires rest or a substantial reduction in activity. Thus, when patients report being exhausted in the morning, it is likely that sleep deprivation and depression are the cause of the exhaustion rather than PBC. Most people with PBC report that a nap does not rejuvenate them. Conversely, many PBC patients inexplicably experience occasional days without a loss of energy.
In summary, the main characteristics of fatigue due to liver inflammation in PBC are:
- Fatigue is often absent in the morning
- Rapid decrease in energy later in the day
- Failure to rejuvenate with a rest period
- Occasional days without fatigue
Just about as common as fatigue in PBC, itching (pruritus) of the skin affects 66% of patients at some time during the disease. The itching tends to occur early in the course of the disease, when patients still have good liver function. As a matter of fact, itching can even be the initial symptom of PBC.
It is interesting to note that some women with PBC experienced itching during the last trimester (three months) of a prior pregnancy, before they knew about their PBC. In a condition called cholestasis of pregnancy, some otherwise normal women during the last trimester develop cholestasis and itching that resolve following delivery. (Remember that cholestasis means decreased bile flow.) Of course, most women with cholestasis of pregnancy do not go on to develop PBC. Yet, it turns out that about 5% of women diagnosed with PBC give a history of having had such itching during a prior pregnancy.
Characteristically, the itching in PBC begins in the palms of the hands and soles of the feet. Later, it may affect the entire body. The intensity fluctuates in a circadian rhythm, meaning that the itching can worsen at night and improve during the day. Nocturnal itching can disrupt sleep and lead to sleep deprivation, fatigue, and depression. Rarely, the itching is so severe and unresponsive to therapy that the person may become suicidal. Prolonged itching and scratching causes scratch marks (excoriations), thickening, and darkening of the skin.
The cause (etiology and pathogenesis) of itching remains unclear. The bile acids, as previously mentioned, normally are transported in bile from the liver, through the bile ducts, to the intestine. Most of the bile acids are then reabsorbed in the intestine and go back to the liver for reprocessing and recycling. In cholestasis, therefore, the bile acids back up from the liver, accumulate in the blood, and, for some years, were presumed to be the cause of the itching. Modern studies, however, have just about refuted the notion that the itching in PBC and other cholestatic liver diseases is caused by bile acids.
Recently, the itching was considered (postulated) to be due to accumulation of an endorphin, a natural substance that attaches (binds) to the natural receptors (acceptors) for morphine in nerves. You see, nerves in the skin carry the sensation of itching. Indeed, the finding that itching improved in some people treated with drugs that block the binding of morphine or endorphins to nerves supported this consideration. Yet, many patients do not respond to these blocking drugs, suggesting that other causes or mechanisms are involved in producing itching.
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