Interpretation of PFT

[infoseek1]

My wife (Asian, 39) has GERD and seasonal allergies. This year she has had a persistent cough triggered by her allergies. She went for a PFT + methocholine challenge. The FEV1 showed 74% of pred, with only 3% improvement Post-Rx. The challenge test showed a drop of 22% in FEV1, leading to interpretation of airways hyperactivity. Also, the TLC showed 46%, leading to interpretation of severe restrictive defect.
However, even now, she can jog, has no breathing difficulty, works part-time, cares for 2 children without problem.
Can someone tell if the test was faulty, based on this information?
Also, is the 22% drop in FEV1 significant enough to warrant treatment.

[National Jewish]

Normal pulmonary function test (PFT) values are based on height, age and gender.  Most predicted values are based on the lung function of European Americans.  It has been shown, however, that normal lung function of Asian Americans is 6 to 7% lower than the European American standards.  The function of Afro-Americans is 12 to 15% lower than the European American standards.  This does not mean that your wife's values are within the normal range.  Generally a 20% drop in forced expiratory volume in the first second of exhaling (FEV1) during a methacholine challenge is considered positive for asthma.  Also a 20% increase in FEV1 after using an inhaled bronchodilator is considered positive for asthma.  Generally this would warrant asthma treatment.

Some of the information you have provided is conflicting.  The significant drop of 22% during the methacholine challenge that suggested airway hyperactivity should have been followed by a greater improvement than 3% in the FEV1 after using an inhaled bronchodilator.  With such a low total lung capacity (TLC) at 46% restriction generally there would be a very high FEV1/FVC ratio.  The cough could be allergy related, but it could also be a sign of asthma.

My recommendation is that the PFT be repeated and interpreted by a board certified pulmonologist.  That your wife can jog and does not experience shortness of breath suggests that the PFT results may be in error.

[Ellis7]

The positive result of the methacholine challenge indicates she might have cough variant asthma. This can be triggered or exacerbated by post nasal drip from allergies or/and GERD.
Often an albuterol inhaler is tried to see if it helps control symptoms. See:

http://www.pulmonologychannel.com/chroniccough/causes.shtml
Chronic Cough Causes

http://www.pulmonologychannel.com/chroniccough/diagnosis.shtml
Chronic Cough Diagnosis
Excerpt:
"The most important measurements obtained during lung volume determinations are residual volume and total lung capacity (TLC). These measurements vary with age, height, weight, and race and are usually expressed as an absolute number and a percentage of what is predicted with normal lung function...................
A low TLC suggests a restrictive ventilatory defect and another pulmonary process may be involved. "