Long-Term Follow-Up in a Male Patient with Micro-TSH-Oma Diagnosed at 8-Yr-Old

Background : TSH-secreting pituitary adenomas (TSH-omas) are very rare and an infrequent cause of thyrotoxicosis. Case Report: A 7.9-yr-old boy was referred to our Pediatric Endocrinology Unit due to a goiter. On admission, patient was thyrotoxic with diffuse goiter. Laboratory evaluation suggested inappropriate TSH secretion as the cause of hyperthyroidism: high serum TSH in presence of elevated levels of TT 4 , TT 3 and fT 4 , and TSH unresponsive to TRH stimulation and to T 3 suppression. Initially, α-subunit (aSU) was in the upper limit of normalcy and pituitary MRI was normal. One year after, patient was still hyperthyroid, despite regular use of methimazole; TSH was 12.6 mU/mL, αSU was elevated and MRI detected a pituitary 8 mm width adenoma, establishing the diagnosis of TSH-oma. Peak GH (ng/dL) on ITT and TSH after TRH were 5.9 and 4.2, respectively. Cortisol and prolactin (PRL) responded normally to ITT and TRH tests. Transsphenoidal surgery was done and, postoperatively, transient diabetes insipidus and adrenal insufficiency ensued. Two and five months after surgery fT 4 , TT 4 and TT 3 were normal, albeit peak TSH after TRH was 1.54. PRL and GH were unresponsive to adequate stimuli. Fourteen months after surgery, TT 4 , TT 3 and fT 4 were low normal. He presented with low IGF-1, low GH peak on dinanic tests and hypogonadism and was treated with recombinant human growth hormone (rhGH) and testostenone. At 16 yr-old, we reached final height, above target height. Conclusion : TSH-oma may be an etiology of thyrotoxicosis in children. To our knowledge, this is one of the youngest patients with TSH-oma yet reported.