A 10-year-old child presents with history of chronic sinusitis and multiple nasal polypi. He also suffers from recurrent chest infections and malabsorption syndrome. Which one of the following tests would be useful for diagnosis?: (A) Total IgE estimation, (B) ESR, (C) Level of angiotensin converting enzyme, (D) Sweat chloride
Answer is D. Presence of chronic sinusitis, multiple nasal polypi and malabsorption point towards cystic fibrosis and therefore sweat chloride test would be useful.