This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
All of the following reduce T4 absorption except 
Select and explain. 
A. Metformin, B. Iron salts, C. Raloxifen, D. Colsevelam
A: Metformin
Answer: A: Metformin 
Explanation: Refer Goodman Gilman 12/e p1136 Absorption of T4 is reduced by Antacids Bile acids binding agents Calcium carbonate Iron salts Proton pump inhibitors. Raloxifen Sucralfate