Re: pft/genetics questions

[Guest guest]

Hi ;

Our doctors always look to the FEV1 (Forced Expiratory Volume in 1

second -- the amount you can blow out in 1 second) and use that as the

main measure of evaluating lung function -- though the other numbers are

all important, too and can indicate different things such as air

trapping and total lung capacity.

The FEV1 generally is reported in 2 ways: in litres (actual amount) and

in the percent you blow compared to what would normally be predicted for

someone of your sex, age, height, weight and race (race is not always

adjusted for). Height is more important in affecting the percent

predicted formula than weight.

I think it is more effective to compare percent predicted from one

visit to another because it accounts for any changes in age, height (as

a patient is growing) and in weight. One may blow the same number of

litres even though lung function has deteriorated if they have gained in

weight or some other measure that changes the formula. In the latter

case, litres stay the same but the " percent predicted " goes down to

reflect the change in lung function.

Keep in mind that PFTs are only one measure and they do not /always/

correspond with lung health. For instance, after some aggressive

treatment with meds, my son's PFT numbers didn't budge, yet the x-ray

showed significant clinical improvement. Go figure. We also had the

experience at a clinic visit of him coughing more than usual and feeling

congested and yet the FEV1 was the best he'd had in 2 years! Go figure,

again! My son rationalized that all the coughing he'd been doing must

have improved his lung power -LOL.

One site that discusses Pulmonary Function Testing and what the

different values refer to is at www.mycysticfibrosis.com. Check the

archives for Jan 5, 2003 as Torsten had sent a description of pulmonary

function tests at that time.

Regarding unknown mutations: yes it is possible to have 2 unknowns as

others on this list or cystic-l will tell you from their personal

experiences. Lab errors are also possible.

If your daughter has rare mutations, that is useful to know, even if you

don't know what they are. For any relatives who may want carrier

testing, they need to know that your family mutation is not going to

show up in the regular screening tests, just as they did not show up for

Emma. r testing may not be possible for them at this time.

Science is not advanced enough to have treatments specific to mutations

so the implications for Emma at this time are not particularly

significant, as long as her diagnosis is not called into question.

It must be frustrating to get unknown results but even more frustrating

to have them discussed by someone with incorrect information! I hope you

did get a copy of the report.

M

Wilkins wrote:

>...

>1. Emma did her first successful PFTs. ... I still don't know which number is

the most

>relevant. ...

>

>2. ...

>

>Is it possible to have TWO unknowns [mutations]? COuld they have

>gotten the wrong blood? If that result is correct,

>what does that tell me?

>

[Guest guest]

Also keep in mind that PFTs change throughout the day, whether you

feel well or not.

All PFTs are usually lower in the morning. So if you feel great and go

to a morning clinic check up and have lousy PFTs it's often not an

accurate picture. You could repeat the same test in the afternoon and

have higher PFT numbers.

Same in reverse: you feel lousy, go to the doctor in the afternoon and

do a PFT, and the doctor reads it and says, " Well, your numbers are

unchanged or up over the last visit... " Be sure to think, " Were my

last PFTs done in the am or pm? "

The only time this would be skewed is for example, you dash to the

doctor for say, a 1:00 appt., but you only got out of bed at a couple

hours prior. Then your 1:00 pm PFT is basically an am PFT test.

Confusing, yes?

Also it's very, very important to know that magnesium deficiency

causes lower lung function. Generally it's lower FEV in females and

lower FVC in males. I think, I may have that backward.

Kim

Keep in mind that PFTs are only one measure and they do not

/always/ correspond with lung health. For instance, after some

aggressive treatment with meds, my son's PFT numbers didn't budge, yet

the x-ray showed significant clinical improvement. Go figure. We also

had the experience at a clinic visit of him coughing more than usual

and feeling congested and yet the FEV1 was the best he'd had in 2

years! Go figure, again! My son rationalized that all the coughing

he'd been doing must have improved his lung power -LOL.