Mannitol Test

[Homely2]

I have just been given my mannitol test results of 31 percent reduction in fev1 after 35 mg.

What does that indicate

[Chip_y2kuk]

I got told they are looking for a 20% drop .... so I guess that indicates asthma

Mannitol is a "specific" irritant so it may also indicate the type(s) of asthma .... which may be more interesting.

[sciencepotato in reply to Chip_y2kuk]

They're looking for at least 15 percent cumulative drop over time or 10 percent drop between two consecutive doses.

[runcyclexcski]

I think it indicates that you have a very solid response, and never have to struggle to convince doctors that you have asthma and need help :). I am sure Lysistrata knows more. I wish my tests were this unequivocal.

[sciencepotato in reply to runcyclexcski]

Same here, I wish I didn't have to prove that I'm not taking my asthma meds for fun. I had my mannitol this week and didn't react. Although two days in I'm struggling to get my peak flow back up after the test. Before the test it was my normal peak flow!

[Lysistrata Administrator Community Ambassador]

I had to remind myself while trying to forget my own experiences with this test but yes that's double the required drop quite soon into the test. I found a paper suggesting a 'positive' response (at least 15% drop from baseline) at 35mg or less dosage indicates a high degree of airway hyperresponsiveness *at the time of the test*.

Obviously doesn't mean your airways are always that twitchy but it's a nice positive response which should satisfy a consultant. I also wish I had such clear cut results! I've done this twice, first time was strong positive (but not as strong as yours), second time was negative but also I was crap at doing the spirometry as I was symptomatic and it was an absolutely horrible experience because of the context and my consultant.

I did some reading after that and it is worth remembering mannitol is an 'indirect' challenge test which triggers the airways via a specific pathway, Vs eg methacholine which triggers the airways directly. In my case I suspect I have variable levels of hyperresponsiveness of the type stimulated by mannitol and the second time that part was less active.

Hope that helps! What are they planning to do with the results?

[Homely2 Administrator in reply to Lysistrata]

Very helpful, thank you

My general respiratory consultant is very reluctant to give me detailed results. When I saw him, he just said the results were positive, he would ignore that I was a bit symptomatic during the end of the test, and he was prepared to accept them as proof of asthma, I assumed the result was very marginal from the way he said it.

I was then confused by his reaction to the results. He doubled my alvesco to 640 a day, and changed my fostair 100 mart, to taking eight doses spread evenly over the day, so 800 a day.

He also referred me to cardiac department, asthma physio, and has asked the local asthma tertiary centre to review my file.

So now I have the actual results and everybody's comments, I understand his reaction, though not the cardiac bit.

He also asked me if I wanted to go to the tertiary centre if it was offered. I was not sure, as he said that they would want to re diagnose me again. I have now been diagnosed five times in 2 and a half years, and I am really sick of it. Each time I am diagnosed, I am moved, and then go through diagnosis again. Diagnosis is a pain as I have low eosonophils.

[Chip_y2kuk in reply to Homely2]

If you get the opportunity to go to a tertiary care centre my advice would be... do it.

I've had 4 respiratory referrals and it was the tertiary care centre (the severe asthma team) that got to the bottom of it... its a shame I didn't get sent there earlier.

The cardiac department isn't unusual and is in case it's been overlooked that you have "cardiac asthma" ... which is a type of heart failure that causes asthma symptoms.... your consultant it looks like is being thorough... they told me my heart is as strong as an ox's, although I do have an electrical anomaly,but apparently its not known to cause any problems and we only know about it because we've gone looking (it's a shame the rest of me isnt)