Optimal Thyroid Peroxidase Antibody Levels

One of the most common questions I get is, “What are optimal Hashimoto’s thyroiditis antibody levels?” For years, many patients and clinicians have been chasing thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibody levels in an attempt to get them as low as possible or even undectable as a measure of success.  This can leave many people frustrated and stressed about their condition.  Some individuals feel that these levels should become undetectable in order to consider the condition in complete remission.  But is this entirely true or necessary?

A recent study out of Germany has helped us get a clearer picture of how we should be looking at thyroid antibody levels.  The study is entitled, “Anti-thyroperoxidase antibody levels >500 IU/ml indicate a moderately increased risk of developing hypothyroidism in autoimmune thyroiditis” published in the journal Hormone Metabolism Research.

The authors were specifically looking at thyroid peroxidase and anti-thyroglobulin antibody levels and if they are associated with developing hypothyroidism.  Here is a breakdown of what the authors found:

Patients with TPO antibody levels >500 did show an increased risk of developing hypothyroidism.

Patients with TPO antibody levels <500 did not show an increased risk of developing hypothyroidism.

Patients with anti-thyroglobulin and thyroid peroxidase antibody levels <500 did not show an increased risk of developing hypothyroidism.

Anti-thyroglobulin antibody levels at any level did not show an increased risk of developing hypothyroidism.

Even those who did have elevated TSH after years of follow-up were still considered euthyroid which means they had normal functioning thyroid glands.

They did follow the patients for an average of 6 years which is a fair amount of time to make a good conclusion about how antibody levels potentially cause hypothyroidism.  Hypothyroidism was defined as a TSH >4.6. Free T4 levels weren’t statistically important in any group because they didn’t vary enough to be of concern.

Over the last 15 years, I have found that these study results hold true and that patients are usually feeling great once their antibody levels are below 500.  Some will remain in the 50-400 range no matter how well the patient eats, manages stress, improves gut function, and no matter how targeted their supplement plan is put together.

I have always followed the advice of “Treat the patient, not the labs” so when a patient is feeling great I have always discontinued focusing on these numbers.  Everyone is so unique after all that we can’t completely go by numbers and ranges on laboratory tests.  I do love testing because it almost always reveals deficiencies and imbalances that can be difficult to identify simply by talking to someone.  However, once we get deep into treatment and a patient gets well, these numbers become less and less important.
What is the takeaway?
One potential flaw in the study is the fact that hypothyroidism was defined as a TSH >4.6.  There are some clinicians who believe that the range for TSH is far to broad and that TSH should be within a tighter window such as 1.5, 2.0, or 2.5 as the upper cut-off point.  There is little evidence to support this claim for every single human being who has Hashimoto’s or hypothyroidism.

Sure, some people just feel better with a TSH that is in these lower ranges but some people also feel great with higher TSH levels.  As with everything in functional medicine, this is an individualized question which shouldn’t be set in stone.

Additionally, as pointed out above, the patients who did have TSH levels above 4.6 after the 6 year follow-up had normal thyroid function despite the higher TSH levels.

Once we’ve dealt with the most significant causes of Hashimoto’s thyroiditis including gut health, infections such as Epstein-Barr Virus, food sensitivities like gluten, vitamin D deficiency, selenium deficiency, stress,