TPO Antibodies
What This Test Measures
Antibodies attacking thyroid peroxidase enzyme
Conventional vs. Functional Optimal Range
The gap between these ranges is why you feel terrible with "normal" labs. Conventional medicine waits for disease. Functional medicine optimizes for health.
Gabriel's Take
TPO antibodies show the immune system is targeting the thyroid, often years before thyroid levels change, and most people with Hashimoto's have them (NIDDK). They are common: about 1 in 10 U.S. adults test positive (NHANES), so a positive result is a reason to monitor, not a diagnosis. The chance of developing low thyroid is highest when antibodies come with a rising TSH (Whickham Survey). Gabriel's optimal band is 5 IU/mL or less; a value between 5 and your lab's cutoff means detectable, keep watching. Selenium lowered TPO antibodies in trials (moderate certainty) and gluten-free diets have mixed results, but no diet or supplement has been shown to reverse Hashimoto's or keep it from progressing.
When This Test Is High
Hashimoto's thyroiditis, autoimmune thyroid disease
When This Test Is Low
Normal; no autoimmune attack
Related Conditions
Autoimmune thyroid disease, goiter, thyroid nodules
Recommended Follow-Up
Recheck TSH and free T4 every 6-12 months; ask a clinician about selenium and vitamin D; get tested for celiac disease before trying a gluten-free diet