A 26-year-old woman visited the clinic with a history of asthma and repeated respiratory and sinus infections. She had a persistent daily cough and often had to miss school and work due to asthma attacks. Her gastrointestinal health was fine. The latest spirometry test showed her forced expiratory volume in one second (FEV1) was 73% of what was expected, and bronchodilators had no effect.

An examination of an ED chest x-ray showed slight enlargement and increased thickness in the upper lung lobes. Tests were conducted, including a sputum culture for bacteria, fungus, and mycobacteria, and a chest CT scan. The sputum culture showed growth of methicillin-resistant Staphylococcus aureus (MRSA). The chest CT showed enlarged airways in the upper lung lobes, with the right lobe affected more than the left, and a thickening of the bronchial walls with mucus blockages in a tree-in-bud pattern.

Based on the clinical observations, the patient was tested for  bronchiectasis in the upper lobe. The patient's immunoglobulin levels were normal. The sweat chloride levels were 50 and 52 mmol/L, putting her in the intermediate category. A sweat chloride level of 60 mmol/L or higher is considered indicative of CF.

The patient also underwent genetic testing and was discovered to have the F508del (the most widespread CF mutation) and R117H, a less common variation sometimes present in patients diagnosed with CF in adulthood. The diagnosis was confirmed by the patient's clinical symptoms of CF and the presence of these two mutations.

The patient was eager to start treatment and the healthcare team helped her develop a plan that included airway clearance, exercise, anti-inflammatory drugs, and inhaled antibiotics. The treatment yielded positive results, as the patient reported fewer lung flare-ups and less coughing. After a year of treatment at the CF center, her FEV1 increased to 83% of the expected value.