Which substance has a half-life closest to 12 hours?

Which substance has a half-life closest to 12 hours?

• A. Albumin
• B. Transferrin
• C. Retinol-binding protein
• D. Prealbumin

Answer: (C)

Understanding how quickly different circulating proteins turn over helps identify a marker that reflects recent nutritional changes. Retinol-binding protein has a short half-life, about 12 hours, so its serum level changes rapidly with shifts in protein intake and status. That makes it the best match for a 12-hour half-life. Albumin turns over very slowly, around 20 days, so it doesn’t reflect recent changes quickly. Transferrin and prealbumin (transthyretin) have longer half-lives—roughly a week and about 2 days, respectively—so they’re not as close to 12 hours as retinol-binding protein.

Understanding how quickly different circulating proteins turn over helps identify a marker that reflects recent nutritional changes. Retinol-binding protein has a short half-life, about 12 hours, so its serum level changes rapidly with shifts in protein intake and status. That makes it the best match for a 12-hour half-life. Albumin turns over very slowly, around 20 days, so it doesn’t reflect recent changes quickly. Transferrin and prealbumin (transthyretin) have longer half-lives—roughly a week and about 2 days, respectively—so they’re not as close to 12 hours as retinol-binding protein.