Prealbumin half-life is approximately how many days?

• A. 2-3 days
• B. 4-6 days
• C. 12 hours
• D. 1 week

Answer: (A)

Prealbumin (transthyretin) turns over quickly in the bloodstream, with a half-life of about two to three days. That short half-life makes it a sensitive marker for recent changes in protein intake or status, so its levels rise or fall within days after starting or adjusting nutrition therapy. This contrasts with proteins like albumin, whose much longer half-life (around 20 days) means it reflects longer-term status rather than rapid changes. The other timeframes listed are not consistent with prealbumin’s known turnover rate, so the two-to-three days window best fits how this protein behaves in the body.