Diagnosing Asthma in Toddlers
Diagnosing asthma in toddlers (children under 5 years) is challenging because reliable objective testing is not feasible, and there is insufficient evidence to support an evidence-based diagnostic algorithm for this age group. 1
Diagnostic Challenges in Toddlers
- Toddlers cannot reliably perform spirometry or other objective lung function tests
- Symptoms often overlap with viral respiratory infections
- Wheezing episodes may be transient and not progress to persistent asthma
- Alternative diagnoses may present with similar symptoms
Clinical Assessment
Key Symptoms to Evaluate
- Recurrent wheeze - most important diagnostic symptom with sensitivity 0.55-0.86 and specificity 0.64-0.90 2
- Frequency of episodes - ≥3 episodes of wheezing in past year lasting >1 day and affecting sleep 2
- Symptom pattern - wheeze, cough, and breathing difficulty, especially at night or early morning
- Triggers - exercise, viral infections, allergen exposure, weather changes
- Response to bronchodilators - improvement with short-acting β2-agonists
Risk Factors for Persistent Asthma
- Parental history of asthma
- Personal history of atopic conditions (eczema, food allergy)
- Wheezing without colds
- Peripheral blood eosinophilia
- Diagnosed allergic rhinitis 2
Diagnostic Approach
Since objective testing is not feasible in toddlers, diagnosis relies on:
Detailed symptom history:
- Pattern, frequency, and severity of wheeze, cough, and breathing difficulty
- Triggers and response to previous treatments 2
Direct observation of symptoms by healthcare provider when possible
Therapeutic trial:
- Document objective improvement in signs or convincing parent-reported symptoms with asthma therapy 3
- Reversibility defined as direct observation of improvement with short-acting β2-agonists by a healthcare provider during an acute episode (preferred method) 3
- Alternative: convincing parental report of symptomatic response to a three-month trial of medium-dose inhaled corticosteroids with as-needed SABA 3
Rule out alternative diagnoses:
- Foreign body aspiration
- Congenital airway abnormalities
- Cystic fibrosis
- Primary immunodeficiency
- Vascular ring
- Tracheomalacia 2
Important Considerations
- A single episode of wheeze does not constitute asthma
- Response to bronchodilators in viral wheeze may be variable and does not confirm asthma diagnosis 2
- Regular use of bronchodilators is not recommended for viral-induced wheeze without confirmed asthma 2
- Salbutamol (albuterol) syrup can be used for short-term symptomatic relief in viral wheeze but should not be used as a diagnostic tool alone 2
When to Refer to a Specialist
- Diagnostic uncertainty
- Poor response to initial treatment
- Severe or life-threatening episodes
- Frequent exacerbations despite appropriate therapy
- Suspected alternative diagnosis
Future Diagnostic Approach
For children 5 years and older, the European Respiratory Society recommends:
- At least two abnormal objective test results for diagnosis 1
- First-line tests: spirometry with bronchodilator reversibility testing and FeNO measurement 1
- Challenge testing when other tests fail to confirm diagnosis 1
However, these recommendations cannot be applied to toddlers due to their inability to perform reliable spirometry and other objective tests.
Conclusion
Diagnosing asthma in toddlers remains a clinical judgment based on symptom patterns, risk factors, response to therapy, and exclusion of alternative diagnoses. The European Respiratory Society acknowledges that diagnostic tests for asthma in young children under 5 years are rarely performed, and there is insufficient evidence to support an evidence-based diagnostic algorithm for this age group 1.