Practicing In The Sweet Spot

I strive to practice medicine in the “Sweet Spot” that sits right where medical science and your individual circumstances meet. Medical science tells us how to best treat certain populations, then you and I figure out how to best apply that science to your health. I’d summarize practicing in the Sweet Spot as providing thoughtful and caring guidance, backed up by science.

Suppose you were bothered by fatigue, poor concentration, and depressed mood. You went to see your doctor, and she did some tests which indicated you had low thyroid function, or hypothyroidism. (If you are not familiar with thyroid physiology and hypothyroid symptoms, you might read this handout). Excited to have an an answer to why you weren’t feeling well, you started Levothyroxine (T4) therapy, the standard treatment for hypothyroidism. Yet 4 months and one medication adjustment later, while testing shows your TSH is now “perfect” at 1.3 uIU/mL, you still don’t feel well.
What Now?
It makes sense to consider whether there is not another cause for the symptoms, such as iron deficiency, anxiety, or insufficient sleep. But what if no other explanation is apparent? Well, in 1999 a group of researchers tested a hypothesis that treatment with two thyroid hormones, T4 and T3, would be more effective for treating the symptoms of low thyroid function. In that study they found people felt more energetic, less depressed, and sharper cognitively when they took the combination of two thyroid hormones than when the took Levothyroxine alone. However, since then more than 15 similar trials have been performed, and have failed to confirm the benefit of T3/T4 combination therapy. The summary from available evidence is that T3/T4 combination therapy is not clearly better, nor clearly worse, than standard T4 therapy. Interestingly, in many of these studies there was a subset of people that seemed to prefer the combination therapy.
So what does this have to do with the Sweet Spot I mentioned?
Take a look at the diagram.

Noting the evidence above, guidelines published by the American Thyroid
Association recommend against routine use of T3/T4 combination therapy. To me, this recommendation falls a bit too far to the left of the Sweet Spot. Given the lack of harm and potential benefit of combination therapy, I believe routine use of the “N of 1 trial” (a trial to see how you respond) is warranted, and I routinely try T3/T4 combination therapy in my patients.

Many of patients have also seen alternative medicine practitioners and received advice about their thyroid condition. This advice often includes recommendations: (1) to measure TSH, free T4, free T3, reverse T3, and thyroid antibody levels routinely, (2) to use reverse T3 and thyroid
antibody levels to guide therapy, (3) to avoid eating gluten and dairy, and (4) to treat “adrenal fatigue.” On the diagram, this is where advice falls too far to the right of the Sweet Spot. There is no science to support these recommendations. In the absence of celiac disease there is no evidence that eliminating gluten helps your thyroid condition or your well-being. Why burden yourself with a fairly significant dietary restriction if it will not help? The concept that the adrenal gland is unable to secrete sufficient cortisol when exposed to chronic stress, the main idea behind “adrenal fatigue,” is also unsupported by actual scientific studies. Look, I might
notice that many of my hypothyroid patients who don’t feel well are wearing black shoes, but I am not going to recommend you avoid black shoes until there is evidence for benefit. I want to give you recommendations that are going to be helpful. Going down a road of conjecture and untested ideas is likely to delay or prevent you from finding the true cause of your symptoms.
So, back to the Sweet Spot.
If you have hypothyroidism and come see me, and you have ongoing symptoms of hypothyroidism despite Levothyroxine therapy and a TSH level of 1.3 uIU/mL, I will discuss the option of trying T3/T4 combination therapy to see if it helps you. In my experience you have a 50% chance of responding favorably. And if you don’t respond, we will keep searching for the true cause of your symptoms.
The Sweet Spot. Thoughtful and caring guidance, backed up by science.