Hypothyroidism, also known as low thyroid function, affects about 10% of the population in the United States. Standard treatment is replacement of the T4 (thyroxine) hormone using levothyroxine (Synthroid).

T4 must be converted to a thyroid hormone called T3 (triiodothyronine). This is accomplished by an enzyme called DIO2. Some individuals have a variant in the DIO2 gene that results in the body not converting T4 to T3 as efficiently as it should.

Individuals with hypothyroidism who have a variant in DIO2 often don’t feel as well as they should when taking levothyroxine. These individuals would benefit from additional T3 supplementation in the form of a medication called liothyronine (Cytomel). Alternatively, patients with hypothyroidism can be given a desiccated thyroid medication (Armour Thyroid, NP Thyroid) that contains a combination of T3 and T4.

Since levothyroxine is considered “standard of care”, many prescribers are hesitant to prescribe another thyroid medication, even though it may be exactly what the patient needs. It is

also standard practice to order TSH and T4, often neglecting to look at T3 levels which are incredibly important.

A nutrigenomics test will let you know if you have this variant in DIO2 and may help you convince your doctor to explore a different treatment option if you are not receiving optimal results from levothyroxine.

In addition, the DIO2 gene variant appears to be associated with poorer blood sugar control in diabetics and increased risk for developing insulin resistance. Knowledge of this variant may be the additional piece of information you need to get on a healthier diet path.