Thyroxine is associated with increased metabolic rate and weight loss. However, there is also broad anecdotal evidence that it increases appetite and leads to weight gain in some patients.

Thanks Dr. Ayers. In coincidence of your post, I happened to borrow from the library at the Oregon Science and Health University, Portland, the 10th edition of Werner & Ingbar's The Thyroid: a Fundamental and Clinical Text. This young woman's condition is most likely nonthyroidal illness secondary to her long-term anorexia (at least 2 years) nervosa. This text and other sources indicate treatment is not beneficial, so I am concerned about her physician's prescription for L-thyroxine without a diagnosis of primary hypothyroidism. I can't see the rationale for suppressing TRH/TSH during recovery especially if she is weight restored and improved psychologically. If you can direct me to any references for evidence-based thyroid supplementation in cases of anorexia nervosa, I would appreciate the opportunity to read those. There seems to be an indication that leptin supplementation would have more of a positive impact on the thyroid and HPG axes if Rx was to be used. Her leptin is still low. Any comment on this?

Let me add that if in the "perturbed or disordered" state, T4 is being converted to reverseT3, I would suspect supplementation/exogenous T4 will be additive to endogenous T4 that is increasingly diverted to producing the active T3 from the inactive rT3 as the normal nutritional/energy state is recovered. Mehler (2001) states that this may occur over a ~6 month period. Thus there is an increased "pressure" to suppress what is currently a normal TSH. Therefore I suspect that T4 supplementation is contra-indicated unless primary hypothyroidism is confirmed after several months of observation and serial lab tests. Comments? Thanks again.

I note that you haven't said anything about the T3 (free or total). You would really need to have T3 be low as well to entertain a diagnosis of hypothyroidism.

That being said, I suspect the low free T4 with a normal TSH is a central (hypothalamic) adaptation to starvation (ie a "sick euthyroid" variant) as is the amenorrhea.

I can recall one patient I saw with anorexia who had a similar picture (including a low BMR by indirect calorimetry in her early refeeding state). Over several months her levels returned to normal as did her BMR.

I would be inclined to think that as long as there is evidence that the pituitary function is coming back on line with rising estrogen and gonadotropin levels, that watchful waiting would be reasonable.

Dr. Steed, Thanks for your response. The latest from the Dr. is that she is prescribing it for mood elevation and the delayed menses. The patient refuses antidepressants. By my postings you can see I have some idea of the endocrine dynamics; however, do you believe, albeit from what little information I have posted, that there may be any clinical or otherwise harm done by a couple of months of L-thyroxine? The patient will probably be followed by serum hormonal and cytokine (leptin) levels every other week for some time to come.

I think that as long as she doesn't give so much replacement so as to suppress the TSH to below normal, I wouldn't worry about ill effects. The main consequence is that as long as there is replacement, the need for the pituitary-thyroid axis to recover will be less and it can be delayed.

Dr.Makovsky, you are right! The case appears to be that of Non-thyroidal illness (NTI). We have seen many cases of NTI and in almost no condition Thryoxine replacement has been needed. The primary objective should be to treat the primary disease. I think serum free T3 and reverse T3 levels would shed light on the thyroid/metabolic status of the patient and must be obtained before starting any L-Thyroxine therapy. The high T4 (and hence Free T3) would push the menstruation further under suppression and, at least, result in delayed recovery from amenorhoea. The L-thyroxine could (in this case) be given only if Free T3 is also low and that also with good monitoring.

Thanks for the responses.

Dear colleague,

I have some patient s in my group with after refeeding still a higher TSH and low FT4.You must control the antibodies ,because you can have a hashimoto thyroiditis and then thyroxine is indicated.when the patient is still in undernutrition with very low BMI's then I advice after 24 hr iodium extretion(mostly low) jodit 100 microgram:daily and refeeding and check up after 2 or 3 months.

Yous sincerely

Martine Docx pediatrician-chronic diseseases-eating disorders(tertiary center) Antwerp Queen Paola

Hi! I’m in a similar situation. I didn’t have anorexia, but went through some caloric restriction for some time. My estrogen levels are slowly rising, but still amenorrheic. I have low T4, low T3 and low-normal TSH.

Louis Macovsky , has she recovered? Do you think the L-thyroxine helped? My doctor is thinking about iniciating treatment with thyroid hormone.

Thank you for all the answers!

Louis Macovsky I was wondering if you could advise me. I have been considerably underweight (BMI 11-16) for the last 6-7 years with anorexia as well as overtraining syndrome. I have managed to gain 10kg recently and am eating a very high calorie diet in order to recover. However despite my weight gain over the last 3-4 months my thyroid functions have continued to decline to the point where my doctor has now diagnosed me with hypothyroidism and is wanting to put me on thyroxine. I am skeptical about this, since I myself am an exercise physiology masters student and have sound knowledge of the endocrine system. My thoughts were that my secondary hypothyroidism would naturally reverse with weight regain however it is continuing to get worse. I thought either my thyroid functions are very slow to respond or the problem is more likely to do with my exercise volume (causing HPA-axis dysfunction and thereby affecting the thyroid) which I have not decreased despite eating more and gaining 10kg. Do you think my thyroid would eventually normalize if I kept increasing my food intake and weight despite keeping my high training volume the same? Also what is your opinion on thyroxine treatment for overtraining-induced hypothyroidism? Your time is greatly appreciated

Benjamin, I can't advise you as I am not an MD nor your care provider. Treatment for low thyroid hormone levels in anorexia nervosa has been used on a temporary basis until thyroid values return to normal and the patient has clinically improved. I suggest you continue to engage with your medical care provider and maybe consider a consultation with a nutritionist.

Many thanks Louis! This is very helpful. I will discuss with my doctor and will trial a temporary small dose as she recommended and hopefully after full weight restoration my thyroid levels will normalize. I am already seeing an eating disorder specialist dietician.