What is the best next step for a 6-year-old boy with thick sputum, sinus congestion, and a likely diagnosis of cystic fibrosis?

The next best step for the 6-year-old boy showing symptoms consistent with cystic fibrosis is to refer him to pulmonology for a sweat chloride test. Cystic fibrosis is a genetic disorder often characterized by thick, sticky mucus secretions, which can lead to respiratory issues and chronic sinus congestion. The sweat chloride test is a diagnostic tool used to confirm cystic fibrosis; it measures the concentration of chloride in sweat, with elevated levels typically indicating the disorder.

In the context of this case, it is important to obtain a definitive diagnosis before initiating specific treatments. The sweat chloride test is considered the gold standard for diagnosing cystic fibrosis, as it directly assesses the underlying defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene function.

While other treatment options may be relevant once a diagnosis is confirmed, they are less appropriate as the immediate next step. For example, inhaled hypertonic saline may help manage symptoms in those already diagnosed but is not a diagnostic tool. Similarly, the use of antibiotics, like azithromycin, might be employed later to address respiratory infections often associated with cystic fibrosis but should also be initiated based on a confirmed diagnosis and the patient's specific clinical needs.

Therefore, referring to pulmonology for