Question

I have asthma. My doctor has asked me to bring samples of my sputum to see if the treatment is working well. What does this mean? What is she looking for?

Answer

In recent years, the role of inflammation of the airways has become more important in measuring the severity of asthma. And one way of assessing this inflammation is to estimate the number of special white cells, called eosinophils because they take-up a red stain, in the sputum. (Eosinophils are generally associated with allergic responses, and asthmatic inflammation is allergy-based.)

A British study (referenced below) has examined whether managing asthma treatment by monitoring eosinophils in the sputum is as good as the more traditional ways of using symptoms as a gauge. The investigators found that using treatment to try to normalize eosinophils counts in the sputum was more successful in reducing attacks and hospital admissions than traditional approaches.

Your doctor is probably using this method to see how well your asthma is controlled, and whether you are at risk of having an attack in the near future.