Zinc, Serum

TIMING: Fast at least 8 hours and draw first thing in the morning. Serum zinc drops throughout the day (roughly 2 µg/dL per hour later in the morning) and rises after meals, making timing critical for accurate results. IMPORTANT: Hemolysis (even minor) falsely elevates zinc because red blood cells contain 10–20x more zinc than serum. If your sample is hemolyzed, request a redraw. Avoid zinc supplements for 24 hours before testing. The functional medicine community notes that serum zinc, like serum magnesium, is an imperfect marker — it reflects only ~0.1% of body zinc. These notes reflect common practices in functional medicine communities.

Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.