Abstract
Mentors: Avin Pothuloori, Marium Ilahi, David Odegaard Program: Internal Medicine – Endocrinology Type: Case Report Background: Thyrotropin secreting pituitary adenomas are the rarest pituitary adenomas, representing 0.5% of functioning pituitary adenomas with a prevalence of 2 cases per million. These tumors secrete active TSH that is non-responsive to thyrotropin-releasing hormone. They are responsible for less than 1% of all hyperthyroidism cases. Case: A 47-year-old male with a medical history of cardiomyopathy and atrial fibrillation requiring multiple cardioversions and ablations presented with palpitations and was found to be in atrial fibrillation with rapid ventricular response. Lab workup revealed elevated Free T4, Total T3 and Free T3 with a normal TSH. He was treated for hyperthyroidism and discharged on methimazole and propranolol. He was readmitted for atrial fibrillation with rapid ventricular rate, labs on admission were consistent with central hyperthyroidism; TSH, free T4, total T3 and TSH alpha-SU were elevated, Sex hormone binding globulin was in upper normal range, thyroid antibodies were negative, and insulin like growth factor 1 was elevated. The growth hormone suppression test was negative. The thyroid ultrasound was normal and pituitary MRI w/wo contrast confirmed a 1.6 x 6.0 x 8.0 mm microadenoma within the left side of the pituitary gland. Methimazole was discontinued and beta-blockade was continued. He was seen by neurosurgery. He is currently on surveillance and medical management with octreotide and beta blockers as the patient would like to avoid surgical intervention. Conclusion: This case highlights the importance of considering Thyrotropin secreting pituitary adenomas rare in patients with cardiovascular disease and hyperthyroidism.