Ask the doctor: What is the condition called sepsis?

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Ask the doctor

Q. Can you please explain what sepsis is? What happens in the body to make it fatal?

A. Sepsis is one of several conditions in which the immune system, which is meant to protect us from things foreign (like germs), goes awry and injures us instead. The disordered activity of the immune system that we call sepsis doesn't just start out of the blue. Instead, it is often triggered by another serious condition that is urgently calling on the immune system to help the body heal. Often, the condition that triggers sepsis is an infection (particularly infection by bacteria). However, other things also can lead to sepsis: autoimmune diseases, surgery, or severe burns, for example.

Things go wrong when the activated cells of the immune system that are trying to help the body heal instead go over-board. The immune response is both too vigorous and too prolonged: it can't quiet itself down when it needs to. It's as if the immune system has developed a problem with anger management, and the angry response becomes dysfunctional.

Sepsis is pretty common; it is estimated that there are one million to two million cases every year in the United States. Twenty years  I was one of those cases—I was pretty sick for a few days, but recovered fully. I had many of the cardinal features of sepsis: fairly suddenly, I felt completely exhausted and had a very high fever, a rapid heart rate, rapid breathing, low blood pressure, pale and mottled skin, very high numbers of white blood cells, very high blood markers of inflammation (as shown on tests for erythrocyte sedimentation rate and C-reactive protein), and somewhat low levels of oxygen in the blood. I don't think I had an alteration in my mental state, as some people with sepsis do. On the other hand, if my mental state had been altered by sepsis, would I know that it had been? At least, no one told me that my mind was addled (or more addled than usual).

If sepsis is not promptly recognized and treated, it can cause the lungs, kidneys, liver, heart and brain to fail, and can lead to death. Acting immediately is critically important.

Some people appear to be at increased risk of developing sepsis, for reasons we don't understand: people over age 65, people with diabetes, people with cancer, and people who are taking drugs that suppress the immune system. Two common bacterial infections that can cause sepsis, particularly in older people, are pneumonia and urinary tract infection. Both may start with deceivingly mild symptoms, but then suddenly produce more severe symptoms when sepsis begins. That's why it's especially important for older people to call their doctor promptly if they develop an unusual cough or breathlessness (possible symptoms of pneumonia) or painful and frequent urination (possible symptoms of urinary infection). Genetic factors probably also influence a person's vulnerability to getting sepsis. 

- Anthony L. Komaroff, MD
Editor in Chief, Harvard Health Letter