Medicine An infant has a positive newborn screening test for cystic fibrosis. What cut off of sweat chloride confirms cystic fibrosis? A Sweat chloride > 30 mEq/L B Sweat chloride > 40 mEq/L C Sweat chloride > 50 mEq/L D Sweat chloride >60 mEq/L 💡 Explanation An infant has a positive newborn screening test for cystic fibrosis. What cut off of sweat chloride confirms cystic fibrosis? ✓ Correct Answer: D. Sweat chloride >60 mEq/L