What is the half-life of transferrin?

• A. 8-10 days
• B. 1-2 days
• C. 12 hours
• D. 20 days

Answer: (A)

Transferrin has a relatively slow turnover in the bloodstream as the body's main iron-transport protein. The half-life is the time it takes for its plasma concentration to fall by half if new transferrin isn’t being produced. In adults, this turnover is about 8 to 10 days, making it longer than many other circulating proteins but shorter than albumin (which is around 20 days). This long half-life reflects its function as a stable carrier of iron rather than a rapidly changing acute-phase protein.

The other time frames don’t fit because 1–2 days or 12 hours would indicate a protein that is cleared or turned over much more quickly, which isn’t characteristic of transferrin. Twenty days is more typical of albumin, not transferrin.