Hepatitis C and Thyroid Hormone Levels
Thyroid hormone levels can be affected by hepatitis. Chronic hepatitis C is associated with a hypothyroidism, which is underactive thyroid function. It has not been associated with hyperthyroidism, which is overactive thyroid function.
Anti-Thyroid Antibodies
The development of hypothyroidism in chronic hepatitis C appears to be at least partially caused by anti-thyroid antibodies. Antibodies are proteins that normally help your body fight infection. Sometimes, for unknown reasons, a person can produce antibodies that turn against one’s own body, creating an autoimmune reaction. These anti-thyroid antibodies prevent the thyroid gland from producing proper levels of thyroid hormones, resulting in hypothyroidism.
Interestingly, thyroid function does not typically improve after medical treatment for hepatitis C. But after a liver transplant, thyroid function can improve and the anti-thyroid antibodies can decrease.
Hepatitis C and Thyroid Cancer
Due to its effects on the liver, hepatitis C substantially increases the risk of hepatic (liver) cancer. Hepatitis C is also associated with an increase in several other types of cancer, including lymphoma, pancreatic cancer, and thyroid cancer.
Your liver plays a role in producing proteins necessary for maintaining the adequate function of your immune system. Most people know that the immune system works to fight off infections, but it also helps protect against cancer. The effect of hepatitis C on the immune system is believed to play a role in the increased risk of thyroid cancer with hepatitis C.
Yet, it is not known why hepatitis C—rather than other types of hepatitis, which also affect the liver—causes this effect. It is also not known why hepatitis C raises the risk of certain types of cancer, but not others.
Interferon Therapy and Thyroid Disease
Pegylated interferon and ribavirin (PegIFN-α/RBV) therapy is a type of immunologic treatment used for hepatitis C infection. It decreases the viral load, which is the amount of virus in the body, and it reduces many of the symptoms and effects of hepatitis.
This treatment is believed to cause hypothyroidism in some people and hyperthyroidism in others. This link between PegIFN-α/RBV and thyroid disease has been noted for years.
The thyroid symptoms and alterations of thyroid hormone generally do not improve if the medication is discontinued.
A Word From Verywell
If you have chronic hepatitis C, your primary concern is certainly related to your liver function. There are some other effects of hepatitis C infection as well, which are described as extrahepatic manifestations of the disease. Thyroid disease is one of the concerns with chronic hepatitis C infection, and it is often recommended that periodic thyroid function tests be obtained so that the symptoms of thyroid disease can be diagnosed and treated, if necessary.
