Increased Levothyroxine Requirements in Pregnancy — Why, When, and How Much?

Those with sufficiently long memories must be somewhat bemused by the successive controversies surrounding the treatment of primary hypothyroidism, a condition viewed by many as simple, satisfying to manage, and very much within the purview of the primary care physician, rather than the specialist. The development of sensitive assays for measuring thyrotropin has led to a reduction in levothyroxine doses; in most patients, a dose of only 100 to 125 μg daily restores serum thyrotropin levels to the reference range, thereby satisfying the 1990 recommendations of the American Thyroid Association,1 which have since been reinforced.2 There is no consensus, however, . . .