EDP column by Dr Ketan Dhatariya

“My doctor tells me I have an underactive thyroid due to an overactive immune system. My cousin has an overactive thyroid. What has caused this?"

Your immune system is present to help fight ‘bugs’. It is normally able to distinguish your own cells from cells that come from the outside. If, for example, you inhale a bug up your nose, your immune system would be able to tell that that bug is not part of you, and would produce antibodies to the bug. These antibodies would latch onto the bug and destroy it, in an attempt to keep you healthy.

However, in some people the immune system fails to make the distinction between ‘self’ and ‘non-self’ and begins to attack the normal cells within the body. When this happens it is known as an ‘auto immune condition’. There are several of these and they may attack very specific parts organs, such as the thyroid, or they may attack different parts of the body, such as in rheumatoid arthritis. It gets a little more complicated sometimes, because instead of the antibodies destroying a cell, it may make the cell over active. A good example of this is an overactive thyroid in a condition called Graves’ disease – named after the person who described it in 1835, Robert Graves (1797–1853) in Ireland.

These conditions tend to run in women of child bearing age (although men can get them as well), and it is thought, therefore, that it is the female hormones that are partly responsible for these conditions.

These conditions also run in families, but it may be that one member of the family has one autoimmune condition, and another has something else. It is always worthwhile asking members of your extended family if they have any medical conditions because they may be relevant. Other examples of autoimmune conditions include vitiligo (patches of skin without pigment), certain kinds of anaemia, coeliac disease (where the person cannot eat gluten in their diet), and type 1 diabetes.

Because the immune system is vital to help fight bug, the treatments for these conditions often tackles the result of the over activity, rather than the cause itself. So even though it is a problem with the immune that is cause the thyroid problem, the treatment would be replacing the hormone produced by the thyroid. Only in very severe cases is the immune system suppressed, as this often leaves the body vulnerable to attacks from real bugs.

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