Tsh-oma or Thyrotropinoma is a condition in which there is a pituitary adenoma that secretes TSH in an autonomous fashion, resulting in hyperthyroidism with its clinical aspects and complications. It is a very a rare condition comprising less than 0.1% of pituitary adenomas.

The diagnosis and evaluation of Tsh-oma are challenging, as the clinical manifestations and the biochemical profile resemble the thyroid hormone resistance syndromes. Therefore, a high index of suspicion is required.

Down syndrome is a chromosomal disease (trisomy 21) manifested in clinical, physical, and developmental impacts on affected persons. It is associated with thyroid autoimmune diseases and thyroid hypoplasia (congenital hypothyroidism) however, to our knowledge, there have been no described cases in the literature where Down syndrome was associated with a TSH-secreting pituitary adenoma. We hereby present a 34-year-old male known to have Down syndrome who was found to have a thyroid disorder (Tsh-oma) different from the known thyroid disorders linked to Down syndrome.