A 24-year-old woman has a chronic cough that began after a respiratory tract infection 8 months ago. She notices that exposure to cold air and exercise are likely to induce her symptoms. She has no personal or family history of allergy or asthma. On examination, vital signs are normal. Lungs are clear to auscultation. Chest x-ray is normal. On office spirometry, FEV1 85% of predicted and FVC 85% of predicted. The ratio FEV1/FVC is 76%. The flow- volume loop is normal. Pulmonary function testing shows a total lung capacity of 105% of predicted. After the patient inhaled methacholine, there was a 20% drop in FEV1 and FVC Which of the following is the most likely diagnosis?
سؤال مجاني 10 من 10 اليوم · اشترك وكمّل بدون حد
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الإجابة والشرح
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الإجابة: A. Bronchial asthma
The chronic dry cough is triggered by cold air and exercise, and spirometry is normal. A ≥20% fall in FEV1 on methacholine challenge shows airway hyperresponsiveness, which means bronchial asthma (cough-variant type). IPF would give a restrictive pattern. CF and GERD do not cause methacholine hyperresponsiveness.
ليش كل خيار صح أو غلط
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A
ليش صح
A methacholine challenge with a fall in FEV1 above 20% shows airway hyperresponsiveness, supporting asthma when spirometry is normal and symptoms follow cold air and exercise.
✓ Pulmonology 🫁.pdf · p. 6 -
B
ليش غلط
Cystic fibrosis is a differential at 12-39 years that presents with excessive cough and mucus production, not an isolated cough triggered by cold air and exercise with a positive methacholine test.
✓ Asthma & asthma exacerbation.pdf · p. 5 -
C
ليش غلط
GERD is only one of the listed triggers of non-allergic asthma, alongside cold air and physical exertion; it does not explain the 20% FEV1 fall on methacholine.
✓ Asthma & asthma exacerbation.pdf · p. 3 -
D
ليش غلط
Pulmonary fibrosis is restrictive with low total lung capacity. Her TLC is 105% of predicted, so the pattern is not restrictive.
✓ Pulmonology 🫁.pdf · p. 3
- المصدر
- Pulmonology 🫁.pdf · p. 6
Asthma & asthma exacerbation.pdf · p. 2 - المحاضرة
- Asthma · Pulmonology · Module B
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- Respi bank