Background: Anorexia nervosa (AN) is associated with a number of endocrine abnormalities including a low serum free thyroxine level. Hypothyroidism in AN is a recognised condition which is associated with a low normal free thyroxine and triiodothyronine levels (FT4, FT3) with an elevated reverse T3 (rT3). Serum TSH levels are normal or slightly reduced, suggesting a hypothalamic origin to the suppressed thyroid function which is normally left untreated. It is very rare for patients with AN to have low serum T4 and elevated serum TSH levels. To date, there are only two published (Matsubayashi S, et al. Psychosom Med. 1988; Haraguchi K, et al. Endocrinol Jpn.1986) of a total of five patients in the literature with similar biochemical picture. All these patients however were reported as being thyroid autoantibody negative. It is usual practice to leave such cases untreated as thyroxine therapy may risk increased weight loss.
Cases: We report two females who presented with intentional rapid weight loss and primary autoimmune hypothyroidism with elevated serum TSH (32.5±18.5 mu/l) and low FT4 (10.5±3.5 pmol/l) levels. Both patients were found to have positive serum thyroid peroxidase (TPO) antibodies but no goitre. Following replacement with levothyroxine (up to 100 μg daily) both patients demonstrated improved appetite and weight gain whilst undergoing psychiatric interventions for their eating disorder. Long-term follow up of both patients has demonstrated complete resolution of anorexia nervosa and both remain in thyroxine replacement.
Conclusion: Children with AN with elevated serum TSH levels should prompt further testing for thyroid autoantibodies. We recommend that antibody positive patients should have thyroxine replacement in a specialist setting as it may enhance metabolic rate, cardiac function, appetite, psychological affect and aid recovery.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology