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Old 04-08-2012
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Lungs FVC 85% and FEV1/FVC ratio 86%, normal!

How come a FVC 85% of predicted and a FEV1/FVC ratios = 86% can be consider a normal pulmonary function test???

This is part of UW explanation.... Q ID 824... it is mentioned that this patient with this values has normal pulmonary function tests? am I missing something here???

I believe that those values are outside normal range... can somebody explain to me this???

"Disease is very old, and nothing about it has changed. It is we who change as we learn to recognize what was formerly imperceptible." JMC
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Old 04-08-2012
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Depending on ethnicity and other factors, 85% of normal FVC can be a normal pulmonary function test result. I think the normal range is 80%-120%. My FVC is 70% of normal... I guess I have bad genes and the wrong ethnic background (I did a PFT during my respiratory rotation). For instance, South Asians (such as myself) have an average FVC of 80% of what's found in the Caucasian population. That's probably why you don't see many of us winning Olympic gold medals. And why cricket should be in the Olympics...

An FEV1/FVC > 80% can be suggestive of restrictive lung disease in older people who are symptomatic, but that's more due to reduced FVC (below 80%) than increased FEV1. If a young healthy person blows into a spirometer, they'll usually get an FEV1/FVC value of about 85%. But as you get older, your lung compliance increases and your FEV1 decreases, so the normal value for FEV1/FVC goes down to about 70-80%. At that point, an increased ratio becomes pathological.
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