This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Medicine
Transferrin saturation is? 
Select and explain. 
A. Serum iron/TIBC x100, B. TIBC/serum iron x100, C. TIBC/serum iron, D. Serum iron/TIBC
A: Serum iron/TIBC x100
Answer: A: Serum iron/TIBC x100 
Explanation: Ans. A. Serum iron / TIBC x100Transferrin saturation =TIBCSerumiron x100Usual valuesNormal reference ranges are:a. Serum iron: 60-170mg/mlb. TIBC:240-450mg/mlc. Transferrin saturation: 15-50% (males), 12-45% (females)