Which is a primary symptom of cystic fibrosis?

Excessive sputum production is a primary symptom of cystic fibrosis due to the accumulation of thick, sticky mucus in the airways. This mucus obstructs airflow and creates an environment conducive to bacterial infections, leading to chronic respiratory issues. Individuals with cystic fibrosis often experience frequent cough and difficulty breathing, both of which are directly related to the overproduction and abnormal viscosity of mucus in the lungs. This excessive sputum can also contribute to further lung damage and related complications over time.

In contrast, conditions like bradycardia, jaundice, and hypertension do not directly relate to the hallmark features of cystic fibrosis, which primarily affects the respiratory and digestive systems due to the defect in the CFTR gene.