Which laboratory marker is used to assess zinc status, and what factor can complicate its interpretation?

• A. Serum zinc levels are used to assess zinc status, but inflammation can falsely lower them.
• B. Serum copper levels are used to assess zinc status and are unaffected by inflammation.
• C. Hair zinc concentration is the most reliable marker of zinc status.
• D. Urinary zinc excretion is the primary indicator of zinc status.

Answer: (A)

Measuring zinc status relies on serum zinc concentration, but its interpretation is affected by the body's inflammatory response. Inflammation triggers an acute-phase reaction that lowers circulating zinc as it is redistributed to the liver and other tissues and as transport dynamics change. So, a low serum zinc can reflect inflammation rather than true zinc deficiency, and a normal value during inflammation doesn’t rule out a deficiency once the inflammatory state resolves. Other factors like time of day, recent meals, and hydration also influence serum zinc, so fasting state and timing matter.

Hair zinc isn’t a reliable marker due to contamination and variable correlation with body stores, and urinary zinc excretion mainly reflects recent intake and renal handling rather than overall zinc status.