Levothyroxine in TPOAb-negative patients with subclinical hypothyroidism

Is there ever a need for hormone replacement therapy with levothyroxine in thyroid peroxidase antibody (TPOAb)-negative patients with subclinical hypothyroidism?

Leonard Wartofsky, MD: I think the question relates to, “Does one treat subclinical hypothyroidism in any situation?” There are different opinions and positions on this. There are professional organizations where some would say, “Yes, clearly,” and others would say, “It depends on how high the thyroid-stimulating hormone (TSH) is.” They might say to not initiate therapy until the TSH is 10 mIU/L or greater. To me this does not make very much sense. For example, if one had a patient who was already taking thyroxine (T₄) and you have them back for a follow-up visit and the TSH comes back at 9 mIU/L, would you not increase the dose of T₄? What is the difference between that patient and a brand new patient in whom you discover a TSH of 9 mIU/L with a normal T₄?

I think it is important to always think about what the true reference range for TSH is that we all have, our individual range within the population, and we should try to reproduce that range—if necessary, with T₄ therapy.