A 38-year-old bakery worker reports cough and wheeze that worsen through the working week and improve over weekends. Skin prick tests to common aeroallergens are negative. What is the most appropriate next investigation to confirm the suspected diagnosis?
- A Serial peak expiratory flow recordings at and away from work for several weeks ✓
- B Single post-bronchodilator spirometry performed in clinic
- C Methacholine bronchial provocation test
- D Chest radiograph at the end of a working week
Correct answer: A. Serial peak expiratory flow recordings at and away from work for several weeks
Explanation
Occupational asthma is confirmed by demonstrating work-related variability in airflow, best done with serial PEF measured at least four times daily across repeated work and rest cycles. A single clinic spirometry may be normal between exposures and misses the pattern. Methacholine challenge proves nonspecific hyperresponsiveness but cannot link symptoms to the workplace, and a radiograph has no role in diagnosing asthma.
Reference: Fishman's Pulmonary Diseases and Disorders, 5th ed.
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Written and medically reviewed by the StethoPrep medical team.