Abstract
A 26-year-old woman was admitted to Shimane Medical University Hospital because of galactorrhea and edema. Her serum prolactin (PRL) levels were high (91-94ng/ml) and she had primary hypothyroidism due to post-partum autoimmune thyroid syndrome (Hashimoto's thyroiditis). Serum-free thyroxine (FT 4) level was 0.1ng/dl and serum thyrotropin was over 1,000μU/ml. Antithyroid antibodies were present. An exaggerated response to thyrotropin-releasing hormone (TRH) was observed in both serum PRL and TSH. The other anterior pituitary hormones were suppressed. Her magnetic resonance image (MRI) showed an enlarged pituitary gland. It was suspected that these results were caused by primary hypothyroidism. Replacement therapy with levothyroxine was begun and the hospital's clinical course was followed. Although her serum TSH levels were soon normalized, plasma PRL levels fell six months after the normalization of her thyroid function. The size of pituitary gland gradually decreased and normalized four years after the start of the replacement therapy. Because of the discrepancy among these three markers, it is suspected that the therapies for hyperprolactinemia and for the enlarged pituitary gland were unnecessary in these types of patients with primary hypothyroidism.
