Diagnosis Case Study - Using FeNO to Confirm Asthma Diagnosis and Guide Treatment

Patient profile

Gender/Age: Female in her 20s
Family History: Both parents have asthma and hay fever
History: Repeated misdiagnoses of chest infections, prescribed antibiotics with little relief; previous short-term improvement with Salbutamol and prednisolone, but no formal asthma diagnosis

Symptoms

Persistent cough
Shortness of breath
Wheezing
Night-time awakenings
Exercise-induced breathlessness

Challenges and Diagnostic Approach:

Spirometry: Result: Normal spirometry results, which can often be the case in asthma
Interpretation: Normal spirometry does not rule out asthma
Serial Peak Flow: Result: Significant variability, over 20% variation in readings, indicating possible asthma

FeNO Test: 126 ppb, indicating significant eosinophilic airway inflammation consistent with asthma

Treatment Plan:

Inhaled Corticosteroid (ICS): Based on her elevated FeNO and variable peak flow, treatment was initiated with an ICS.
Patient Education: The patient was educated on the proper use of the inhaler and advised on managing symptoms if they worsened.

Outcome:

Within weeks, the patient’s symptoms dramatically improved. She no longer experienced night-time awakenings, and her exercise-induced breathlessness disappeared.

Follow-up FeNO: A follow-up FeNO test showed a significant reduction in nitric oxide levels back to normal, confirming that the airway inflammation was under control.

Clinical Takeaway:

FeNO testing, combined with the patient’s peak flow diary and medical history, provided crucial evidence to accurately diagnose asthma when spirometry alone had failed to identify the underlying inflammation. This approach allowed for a personalised treatment plan that significantly improved the patient’s quality of life.