Case by case – diagnosing asthma in adults

In this eLearning CPD module, respiratory specialist nurse Maria Eurton discusses common challenges in diagnosis of asthma in adults, using practical examples to clarify how guidelines can be applied in everyday practice in primary care. Read the full module on Nursing in Practice 365 

Learning objectives

This case-based module will support your knowledge and understanding of:

• How to take a focused respiratory history in adults presenting with cough, wheeze or breathlessness, and recognise symptom patterns that may suggest asthma or alternative respiratory conditions.
• Know when and how to use key diagnostic tests including blood eosinophils, FeNO and spirometry, and understand how these tests support or exclude an asthma diagnosis.
• Differentiate asthma from common alternative diagnoses such as chronic obstructive pulmonary disease (COPD), chronic bronchitis, bronchiectasis, upper‑airway problems and reflux, using history, examination and initial investigations.
• Recognise factors that can influence diagnostic test accuracy, including inhaler technique, adherence, comorbidities, smoking history, diet, diurnal variation and environmental exposures.
• Apply best‑practice initial management for suspected or confirmed asthma, including inhaler device selection, inhaler technique optimisation and adherence to guideline‑based treatment pathways.
• Identify red‑flag symptoms that require urgent GP or specialist assessment and understand when escalation of care is necessary.

Note: These cases are examples of scenarios commonly encountered in primary care. All details have been altered to ensure full anonymisation while still reflecting real‑world clinical practice.

Related Article: How nurses can support patients through inhaler changes

Case 1. Is this a simple allergy, or something more?

1. A female in her late 30s presents in clinic with a recent history of wheeze and dry cough triggered by cat exposure. What questions might you ask the patient next?

Asthma symptoms often come and go, and can include cough, wheeze, shortness of breath and/or chest tightness.¹ Allergens such as animal dander are a common trigger for asthma symptoms. Symptoms that start in childhood, or a family history of asthma or allergy can increase the likelihood of respiratory symptoms being related to asthma.²

Therefore, it is important to ask if she has had any similar episodes in the past, including any issues in childhood, and what symptoms she had.³ It is also important to ask if any family members have asthma.

2. The patient explains she was born two months premature and required oxygen therapy post‑birth, and that she used a ‘blue inhaler’ in childhood (especially after cat exposure) and her mother has asthma. What tests should you do next and why?

Children born prematurely have an increased long‑term risk of developing asthma, and this risk is higher the earlier they are born. A large study of more than four million births in the USA showed that asthma risk is about 30% higher in late preterm children and up to three times higher in those born extremely preterm, compared with children born at full term.⁴

If a clinical history is suggestive of possible asthma, the BTS/NICE/SIGN guidelines are very clear in stating that an asthma diagnosis cannot be confirmed without at least one supportive objective test.¹ The first-line objective tests for asthma are to either measure blood eosinophil count or FeNO levels to assess likelihood of eosinophilic, steroid-responsive airways inflammation.¹

3. A recent blood eosinophil count is within the laboratory reference range. Therefore, the patient undergoes a FeNO test. This gives a measurement of 73ppb. What is the appropriate initial management and why?

FeNO ≥50 ppb in adults is considered high and increases the likelihood of asthma by indicating eosinophilic airway inflammation that is likely to be corticosteroid responsive.¹ It is important to note that FeNO has limited sensitivity. Even though high values are specific for eosinophilic inflammation, many adults with asthma, particularly those with non‑eosinophilic or intermittent inflammation, may have normal FeNO levels, meaning a low or normal FeNO does not exclude asthma.²

Related Article: What are the options when a ‘greener’ inhaler results in worsening asthma symptoms?

The combination of a suggestive history (allergen‑triggered symptoms, possible childhood asthma, family history), plus high FeNO supports a diagnosis of asthma. A low-dose inhaled corticosteroid (ICS)/formoterol combination inhaler should be prescribed as first-line treatment for newly diagnosed asthma patients.¹

This patient reports not having any respiratory symptoms aside from when she is around cats, therefore anti-inflammatory reliever (AIR) therapy – used as-required to treat symptoms, would be an appropriate choice.

Only certain budesonide/formoterol inhalers are licensed for as-needed AIR therapy in asthma, so it is import to review local guidelines (for example, the All Wales asthma management and prescribing guideline,⁵ referenced in BTS/NICE/SIGN 2024 guidelines¹ and last updated in 2025) and/or resources such as electronic medicines compendium (emc) to ensure appropriate, safe prescribing. If the patient begins to experience asthma symptoms outside of their known triggers (in this case cats), their asthma review should be brought forward.

Complete the full module on Nursing in Practice 365 today and earn 1.5 CPD points

Maria Eurton is Asthma+Lung UK Respiratory Champion for Hampshire & Isle of Wight ICB, and a Respiratory Nurse Specialist at a Primary Care Network (PCN) in Southampton

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References

1. NICE. Asthma: diagnosis, monitoring and chronic asthma management (BTS, NICE, SIGN). [NG245] 2024
2. Global Initiative for Asthma (GINA). Reports. 2025
3. Asthma + Lung UK (2024). Healthcare professionals | Asthma + Lung UK
4. Crump C et al. Preterm or early term birth and long-term risk of asthma into midadulthood: a national cohort and cosibling study. Thorax 2023; 78 (7):653-60
5. NHS Wales. All Wales Therapeutics and Toxicology Centre. All Wales adult asthma management and prescribing guideline. 2024; updated February 2025