Importance of TSH Target Ranges in Hypothyroidism Management

Antonio Bianco, MD, PhD: That’s a really important point. Normally, we take these patients, and as endocrinologists we want to keep the TSH [thyroid-stimulating hormone] within the normal range, and we’re happy when we tell patients that once we normalize TSH, they should feel better. Now remember Chip Ridgeway, MD, he had that study, the health fair in Colorado, and he assessed how normal was the TSH in the population, and he saw that only 60% of the people had a normal TSH, and that for me was scary. How do you see that? Even though we try, and we put an effort on normalizing serum TSH, we see that this is missing its target, and that many patients don’t have a normal TSH despite all the effort. How do you see this?

James Hennessey, MD, FACP: Well, I certainly agree with you that we don’t hit the standard by putting things into the normal range very often. The majority of TSHs can be normalized and kept there with precise mechanisms of dosing, etc. But I agree with you, beyond the Canaris study, which was Chip’s study, there’s a whole spectrum of studies that seem to indicate that upwards of anywhere from 32% to 54% of TSH values are abnormal when it comes to people on thyroxine when they’re assessed with precise TSH testing.

Antonio Bianco, MD, PhD: It seems we’re doing a better job. Recently, I saw that study using the Kaiser Permanente database, in which up to 80% of the patients that they surveyed had a normal TSH, but still 20% were off target, which for me is eye-opening; it’s concerning. Let’s not forget that many patients don’t even have a TSH measure; that’s even more concerning. We don’t know how many patients with hypothyroidism go back to their doctors every year to check their TSH. Those could be off target as well.

James Hennessey, MD, FACP: Yes. They certainly could be. If they were off target in the old days, we were always struggling to make minor adjustments in thyroid hormone doses and refine the way the patients were taking the thyroid hormone. We had identified issues that came up that made it difficult to normalize the TSH. But recently, I’ve seen several very large and very well conducted studies that demonstrate there are definitely consequences of these off target TSHs and I’ve taken on a real zeal for normalizing TSH and keeping it there.

Transcript edited for clarity