Iodide-induced hypothyroidism in a patient with anorexia nervosa.
A 39-year-old woman who had been suffering from anorexia nervosa was found to have hypothyroidism. Serum T4, free T4, T3, free T3 and TSH were 3.19 micrograms/dl, 0.5 ng/dl, 15.3 ng/dl, 1.2 pg/ml and 162.1 microU/ml, respectively. On careful questioning, she was found to have taken an iodine-rich diet. The serum iodine concentration was 122 micrograms/dl (normal: 4-9 micrograms/dl) and urinary iodide excretion was 13.05 mg/day (normal: less than 2 mg). After withdrawal of the iodine-rich diet, her serum T4 gradually increased and TSH returned to the normal range. She was diagnosed as having iodide-induced hypothyroidism. However, no significant elevation of serum T3 or free T3 was observed. Serum T4, free T4, T3, free T3 and TSH were 7.85 micrograms/dl, 0.8 ng/dl, 13.6 ng/dl, 4.3 pg/ml and 6.02 microU/ml, respectively. The iodide-perchlorate discharge test result was negative. These findings suggest that there exists some unknown mechanism by which a patient with anorexia nervosa may be sensitive to excess iodide. Furthermore, it is of interest to note that in a recovery phase from the hypothyroid state, normalization of serum T4 rather than T3 is well-correlated to TSH secretion.
D000328:Adult; D000856:Anorexia Nervosa / Q000150:complications*; D004032:Diet; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000209:etiology*; D007454:Iodides / Q000652:urine; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013975:Thyroxine-Binding Proteins / Q000032:analysis; D014284:Triiodothyronine / Q000097:blood
D007454:Iodides; D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine