Does taking prednisone (steroids) effect the test result when tested for Cystic Fibrosis?

Question

I am severely asthmatic w/ an immune deficiency and due to recurring pneumonia, I am being sent to be tested for cystic fibrosis. I have been prednisone (steroid) dependent for years. I recently was hospitalized and given high doses IV. My pulmonolgist wants me to have the sweat test done for cystic fibrosis but is aware prednisone may effect the results. At what dose amount would it effect the results of the CF test and how long must past after taking the higher doses before the test can be done?

Answer 1

Hi, I'm a 39 year old CF patient and have never heard of Prednisone affecting the outcome of a sweat test. However, if your pulmonologist has concerns with the validity of the results he/she should check into DNA testing for it. DNA testing is more expensive and is based on the 600 or so most prevalent gene mutations that cause CF so it's not a 100% guarantee either, should it come back negative, and they may have to do additional tests.

Good luck.

Answer 2

Sweat Tests for CF:
0-40 No CF
40-60 Borderline
60 plus Positive

However many people have blood taken to test for the cystic fibrosis gene which is 100% accurate unless its an unknown mutation. Sweat tests are a good predictor but no-matter what you should ask to have geno-typing done. I have known many people with cf fail a sweat-test yet be persistent and be diagnosed with gene-testing. Its a simple test.

Glad to help

Answer 3

I'm an RN who has taught Nursing for over 25 years and have checked out your question in my Medical and Nursing textbooks. I can certainly appreciate your concern about whether your prednisone intake, particularly your recent high doses of I.V. prednisone, has an effect on sweat test results for cystic fibrosis. According to my references, taking prednisone will not affect the result of the test. Good luck to you.