I have seen a few comments online with numbers in the thousands. All i have found in regards to "average" TPO levels is a study in the 2006 Journal of Endocrinology. This study was done in Turkey and showed a 30% decrease in anti-thyroid antibodies after 3 months of 200mcg per day of L-selenomethionine (selenium) supplementation for in women with Hashimotos Thyroiditis. The starting average TPOAb was 803 and after 3 months the average was 572.
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"New research has shown that Hashimoto's patients with high thyroid antibodies report more symptoms than patients with low thyroid antibodies, even if their thyroid function test is normal. In other words, thyroid replacement is not enough to ameliorate symptoms of autoimmune thyroid disease. (5)
(5) Ott, Johannes et al. Hashimoto's Thyroiditis Affects Symptom Load and Quality of Life Unrelated to Hypothyroidism: A Prospective Case-Control Study in Women Undergoing Thyroidectomy for Benign Goiter.Thyroid, 2011; 21 (2): 161 DOI: 10.1089/thy.2010.0191"
Excerpt from the article - Thyroid Disease - Sensible Alternative
Raw numbers are not all that important when it comes to antibodies...the test is basically either positive (elevated) or negative. Actual counts can vary significantly even intraday.
That being said, numbers in the thousands are not unusual. For example, my TPOab was 900+, and my TGab was "greater than 3,000" (they stopped counting!).
Don't concern yourself with the numbers. It looks much worse than it is...