Synopsis
Confirm asthma with variable symptoms plus objective evidence, recognise dangerous mimics and work-related disease, and use phenotype information to guide referral without replacing the core diagnosis.
- Asthma is a clinical syndrome of variable respiratory symptoms and variable expiratory airflow limitation; neither symptoms nor a single test is sufficient in every patient.
- Typical variability includes episodic wheeze, breathlessness, chest tightness or cough that changes over time and with triggers, nights, seasons, work or treatment.
- Before testing, document recent inhaled corticosteroid because it can suppress eosinophils, FeNO and reversibility and make objective confirmation harder.
- For adults with a suggestive history, NG245 begins objective confirmation with blood eosinophil count or FeNO; eosinophils above the laboratory reference range or FeNO at least 50 ppb can confirm asthma in the right context.
- If not confirmed, use bronchodilator reversibility: FEV1 rise at least 12% and 200 mL, or at least 10% predicted FEV1.
- If spirometry is unavailable or delayed, twice-daily PEF variability at least 20% over 2 weeks supports diagnosis; persistent uncertainty may require bronchial challenge or specialist review.
- A normal examination, spirometry or FeNO does not exclude intermittent asthma; repeat testing when symptomatic and review treatment effects.
- Ask every adult with new or recurrent asthma about occupation. Improvement away from work needs serial work/rest-day PEF and early occupational-respiratory referral, not advice to resign before assessment.
- Phenotypes—type 2/eosinophilic, allergic, exercise-related, obesity-associated, aspirin/NSAID-exacerbated or occupational—inform risk and specialist therapy but can overlap and change.
- Never prescribe SABA monotherapy for asthma; once confirmed, use an ICS-containing pathway and a personalised action plan.