An Undiagnosed Tsh-Secreting Pituitary Macroadenoma Found During Pregnancy

Thyroid stimulating hormone (TSH)-secreting pituitary adenoma (TSHoma) is an uncommon cause of thyrotoxicosis, and is even rarer when found during pregnancy. Our patient presented with thyrotoxicosis accompanied by an inappropriately normal TSH level at 10 weeks of gestation during work-up of surgical termination of pregnancy (STOP). Subsequent investigations performed after STOP confirmed the presence of a TSH-secreting pituitary macroadenoma. She was initially treated with anti-thyroid drugs for biochemical control, followed by trans-sphenoidal surgery after STOP had been performed. Her thyroid function completely normalized after the trans-sphenoidal surgery. Our case illustrated the importance of recognizing the syndrome of inappropriate TSH secretion and highlighted several pregnancy-related aspects in the diagnosis and management of TSHoma during pregnancy.