Dr. Amy Nett: I was a little bit unclear on this one because subclinical hypothyroidism is defined by having an elevated TSH. The definition of subclinical hypothyroidism is that you have an elevated TSH, but the T3 and T4 are within normal limits. We actually don’t measure reverse T3 in our practice. We don’t find it to be consistently useful in telling us about the thyroid function itself. It might be telling us more about what’s going on in terms of general inflammation and T4-to-T3 conversion rather than giving us the more direct information about thyroid function specifically.
Then in terms of what subclinical hypothyroidism versus overt hypothyroidism looks like, it depends completely on the patient. As you know, when we start looking at hypothyroidism, it can be difficult to diagnose. A lot of patients will come in saying, “Well, I have hypothyroidism because of my symptoms,” and that’s because they’re tired and they have constipation and their hair’s falling out and they’re gaining weight and they have edema and sort of feel that puffy, fluid retention feeling. Maybe it’s hypothyroidism, but maybe it’s a food allergy. The symptoms are really nonspecific. Some of my patients with subclinical hypothyroidism, they have symptoms of frank hypothyroidism. Other patients with subclinical hypothyroidism are completely asymptomatic, and that’s one of the reasons it’s really difficult to know when you want to treat subclinical hypothyroidism with thyroid hormone supplementation.
Chris and I did a podcast on that, so you can also look up the podcast to learn a little bit more about subclinical hypothyroidism, but what I would generally do when you have subclinical hypothyroidism—meaning the TSH is above 2.5, but T3 and T4 are normal—is look at the symptoms. If the symptoms are suggestive of hypothyroidism, then think about a trial of treatment, but if there’s another obvious cause that could be contributing to those symptoms, whether it’s a dysbiosis, metal toxicity, mold toxicity, food allergy, think about treating that first before you commit them to that. I definitely have patients with subclinical hypothyroidism who you start them on thyroid medication and they instantly feel a lot better, so just be cautious with the dose if you’re going to start thyroid hormone medication. Let people know that palpitations are a side effect. If they start feeling palpitations, decrease or stop the dose completely.
The differential diagnosis for subclinical presentations, again, it’s a pretty long list because those symptoms are so nonspecific, unfortunately.