Dear Tom
I read your article in endocrinetoday.com magazine from January 10, 2009 and wish to reply. To restate your position, being that most people with hypothyroidism and normal thyroid function tests who continue to report complaints typical of thyroid hormone deficiency, are generally suffering from other conditions such as depression, polycystic ovarian syndrome or non-endocrine conditions.
I have heard similar analyses of resistent hypothyroid symtoms many times at endocrine conferences or hallway “round tables”. The speaker generally rolls their eyes and gives a sly smile to the audience while reporting their conclusion (meant to imply frustation at kooky patients and their persistent complaining).
I do not have the definitive study which confirms or refutes this type of conclusion. I do have a few questions for those who hold beliefs similar to yours, however.
First, why is there such a wide range of normal for thyroid hormones, and TSH? For TSH there is almost a 10 fold difference between high and low normal values. Second, why is there such a wide spectrum in the function and tissue location of 5′ deiodinase (to convert t4 to t3)? Additionally, why are t3 levels so exquisitly sensitive to minor metabolic challenges such as missing a meal or coming down with a virus ? Thirdly, do you think a single does of t4 daily can even remotely reproduce the daily variation and rhythm of thyroid hormone economy produced by a normal thyroid-pituitary axis? Given the extraordinary variability of thyroid hormone levels in the blood, I imagine there are at least a billion different combinations of set points for these levels available for each individual. Finally, in all the years that synthetic thyroid hormone has been available and promoted by pharmaceutical companies, where are the studies that show pure t4 preparations are clinically superior to biologic extracts such as Armour thyroid or careful t4 with t3 combination therapy?
I don’t have the answer to these questions either. What I do have is a healthy respect for persistent complaints by hypothyroid patients. Unlike the results you report with combination treatments my success has been much better. I will be happy to help out my fellow endocrinologist who wishes to dismiss these difficult patients, by accepting them into my practice.
Respectfully,
Gary Pepper, M.D.
