This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Sweat chloride in cystic fibrosis 
Select and explain. 
A. Decreased, B. Increased, C. No change, D. May increase or decrease
B: Increased
Answer: B: Increased 
Explanation: Robbins basic pathology 9th edition page no 226, An increase in sweat chloride concentration is a major criteria for the diagnosis of cystic fibrosis. Page no 223: the primary defect in cystic fibrosis is abnormal function of an epithelium chloride channel protien encoded by the cystic fibrosis transmembrane conductance regulator gene at chromosome locus. Thus the epithelium membrane become impermeable to chloride channels