Case study: Diagnosis
A woman in her 20s had been struggling with a persistent cough and shortness of breath for several years. Despite repeated misdiagnoses and ineffective treatments, FeNO testing helped confirm her asthma and led to a successful treatment plan.
Last updated: September 2026
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
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
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.
Within weeks, the patient’s symptoms dramatically improved. She no longer experienced nighttime 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.
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.
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