Should I Get an Immune System Test?

Content provided by the Faculty of the Harvard Medical School

Should I Get an Immune System Test?

Q. I’m 73, in generally good health, but bothered by frequent colds and respiratory infections. I suspect I have a weakened immune system. Are there tests that will tell me if that is so?

A. Doctors order tests of the immune system quite often, but usually for conditions directly related to an immunological problem. And the tests tend to zero in on an aspect of the immune system, not its overall performance. So, for example, a test for a particular antibody, the antinuclear antibody, is often used in the diagnosis of lupus, one of the autoimmune disorders in which the immune system turns against the body. Another example: Doctors monitor the antibody (immunoglobulin) levels of patients with lymphoma or leukemia because levels can drop to dangerously low levels.

Some people do seem to catch colds (viral infections of the upper respiratory tract) more easily than others. Age may be a contributing factor; as we get older, antibody levels drop, and our white blood cells respond less nimbly to fresh infections.

But it’s not good medical practice to start routinely ordering immune system tests for someone bothered by colds. Why? Because medical tests are worthwhile only if they help direct treatment, and we don’t have any proven “immunity boosters.” You’ve probably seen advertisements making that claim for various vitamins, minerals, herbal therapies, and nutritional supplements, but the evidence behind them is skimpy at best.

Still, when patients of mine are convinced by years of experience that a particular treatment helps fend off colds, I don’t discourage them — unless the treatment has proven risks.

And I don’t mean to suggest that immunological tests are never warranted in the case of respiratory problems. Recurrent colds are sometimes caused by allergies. Allergy tests (either blood tests or skin tests) can be helpful in identifying the cause, so that you can take steps to reduce your exposure. A white blood cell count can also be helpful in diagnosing pneumonia.

— Anthony L. Komaroff, M.D., Editor in Chief Harvard Health Letter

Last updated:	August 21, 2006
Reviewed By:	Faculty of Harvard Medical School