Category: Pituitary Disorders/Neuroendocrinology
Objective : Thyroid stimulating hormone (TSH)-secreting tumors make up less than 2% of pituitary tumors. Reported cases of these tumors in patients with Grave’s disease are exceedingly rare. This case highlights the importance of considering the diagnosis in these patients.
Methods : A 66 year-old Caucasian female with history of Grave’s disease presented to our endocrine clinic in November 2013 for evaluation of post-ablative hypothyroidism, treated with levothyroxine (LT4). Data from her electronic health record was reviewed for this case report.
Results : Despite higher doses of LT4, her TSH remained elevated, as high as 15.3 mIU/L (0.358-3.74 mIU/L.) She had weight gain and fatigue. Her free thyroxine (FT4) was elevated, as high as 2.13 ng/dL (0.76-1.46 ng/dL.) She denied palpitations, diarrhea, tremors, headaches, or vision changes. FT4 by equilibrium dialysis was confirmed elevated at 3.7 ng/dL. TSH assay interference was ruled out by negative heterophile antibodies. As labs showed persistent TSH and FT4 elevation without correlation to LT4 dose, other diagnoses were considered. Alpha-subunit, prolactin, cortisol, insulin-like growth factor-1 were all normal. Thyroid hormone resistance mutation was negative. A 5 mm pituitary lesion was noted on Magnetic Resonance Imaging (MRI) in 2010; she refused imaging follow up. Visual field testing showed no deficits. Suspicion rose for a TSH-secreting pituitary adenoma (TSH-oma.) LT4 was titrated to normalize FT4 and prevent iatrogenic hyperthyroidism. She agreed to an MRI in 2016, that showed interval growth of the pituitary mass to 1 cm. TSH and FT4 in October 2016 were 52 mIU/L and 1.80 ng/dL, respectively. Repeat alpha-subunit was high. Neurosurgery referral was made. Surgery was deferred due to lack of compressive symptoms and need for lifelong anticoagulation due to multiple thromboses. She began Lanreotide to reduce TSH and shrink the tumor. Repeat MRI showed decreased adenoma size after completion of Lanreotide. TSH and FT4 improved to 13.60 mIU/L and 1.01 ng/dL, respectively.
Discussion : This case demonstrates the diagnostic difficulty that arose when clinical and laboratory features did not correlate. The patient’s lack of symptoms of hyperthyroidism are in contrast to the typical presentation of a TSH-oma. This was complicated by initially normal alpha-subunit and pituitary hormones, refusal by patient for follow up pituitary imaging, and lack of compressive symptoms.
Conclusion : TSH-omas are rare, and coexistence in patients with Grave’s disease is more rare. Thus, it is vital to consider this entity to avoid clinical complications of missing the diagnosis
LewisGale Hospital Montgomery
I am a resident physician at LewisGale Hospital Montgomery in Blacksburg, VA who is interested in endocrinology.
Section Chief of Endocrinology
Salem VA Medical Center
I received my BS degree from Virginia Tech in Blacksburg, VA. I then received my degree of Doctor of Osteopathy from the Edward Via College of Osteopathic Medicine in Blacksburg, VA. I completed my Internal Medicine residency in 2013 at Lewis-Gale Montgomery in Blacksburg, VA. My fellowship in Endocrinology was completed in 2015 at the University of Tennessee Health Science Center in Memphis, TN. I have been working as the section chief of Endocrinology at the Salem Veteran Affairs Medical Center in Salem, VA since 2015. My position is mostlyl clinical and covers the broad range of general Endocrinology and Metabolism. I truly enjoy taking care of the veterans and teaching resident physicians in the field of Endocrinology.