Thyreotroop adenoom van de hypofyse: een zeldzame oorzaak van hyperthyreoïdie

TSH-secreting pituitary adenoma: a rare cause of hyperthyroidism Central hyperthyroidism is noted in a 35-year-old man with recurrent panic attacks. Thyroid-stimulating hormone-secreting pituitary adenoma (TSH-secreting adenoma) is found to be the underlying etiology. A pituitary adenomectomy is carried out, with regression of the symptoms and hyperthyroidism. TSH-secreting adenomas are rare and cause hyperthyroidism due to autonomous TSH secretion. In addition to hyperthyroidism, dysfunction of other pituitary axes and neurological problems due to local compression may also be present. Biochemically, TSH adenoma is characterized by elevated levels of thyroid hormones without suppression of the TSH concentration. After analytical interference has been ruled out, additional biochemical and radiological investigations are necessary in the differential diagnosis and to establish diagnostic certainty. Neurosurgical resection is the cornerstone of the treatment, although radiotherapy and somatostatin analogs may also be considered.

Pituitary thyrotoxicosis presenting as abnormal thyroid function testing during pregnancy: a case report

Background Central hyperthyroidism is a rare form of hyperthyroidism caused by thyrotrope pituitary adenomas. It is characterized by elevated thyroid-stimulating hormone alongside high thyroxine and triiodothyronine. Goiter is the most common symptom of central hyperthyroidism. Surgical resection as well as somatostatin analog therapy typically achieve resolution of hyperthyroid symptoms and restoration of a euthyroid state. Case presentation We report the case of a 30-year-old primigravida Caucasian/White female who presented with abnormal thyroid function testing results and multinodular goiter during pregnancy. Postpartum, she was found to have multinodular goiter on physical examination as well as persistent elevated thyroid-stimulating hormone with elevated free thyroxine and free triiodothyronine. Magnetic resonance imaging disclosed a large pituitary macroadenoma, and she subsequently underwent resection of the mass. She achieved a sustained euthyroid state postoperatively. Conclusions This case shows how central hyperthyroidism can present without the more apparent symptoms of thyrotoxicosis and that successful resolution of central hyperthyroidism may be achieved postoperatively.

Somatostatin receptor ligands induce TSH deficiency in thyrotropin-secreting pituitary adenoma

Objective Somatostatin receptor ligands (SRL) are useful to control central hyperthyroidism in patients with thyrotropin-secreting pituitary adenoma (TSH pituitary adenoma). The aim of this study was to describe the frequency of thyrotropin deficiency (TSH deficiency) in patients with TSH pituitary adenoma treated by SRL. Design Retrospective study. Methods Patients with central hyperthyroidism due to TSH pituitary adenoma treated by short or long-acting SRL were retrospectively included. TSH deficiency was defined by a low FT4 associated with non-elevated TSH concentrations during SRL therapy. We analysed the frequency of TSH deficiency and the characteristics of patients with or without TSH deficiency. Results Forty-six patients were included. SRL were used as the first-line therapy in 21 of 46 patients (46%). Central hyperthyroidism was controlled in 36 of 46 patients (78%). TSH deficiency appeared in 7 of 46 patients (15%) after a median time of 4 weeks (4–7) and for a median duration of 3 months (2.5–3). The TSH deficiency occurred after one to three injections of long-acting SRL used as first-line therapy in 6/7 cases. There were no differences in terms of clinical and hormonal features, size of adenomas or doses of SRL between patients with or without TSH deficiency. Conclusions SRL can induce TSH deficiency in patients with central hyperthyroidism due to TSH pituitary adenoma. Thyrotropic function should be assessed before the first three injections of SRL in order to track TSH deficiency and reduce the frequency of injections when control of thyrotoxicosis rather than tumour reduction is the aim of the treatment.

SAT-LB55 A Case of Central Hyperthyroidism From a TSH Secreting Pituitary Adenoma

This is a case of a 41 year old Filipino female, with one month history of palpitations, unintentional weight loss and increased frequency of bowel movement. Patient was tachycardic and had a slightly enlarged thyroid on physical exam. There were no cushingoid or acromegalic features. Initial work-up revealed elevated TSH 7.10 U/mL prompting referral to an endocrinologist who had an initial consideration of central hyperthyroidism, MRI was done revealing a pituitary adenoma with dimensions of 7.4 x 11 x 5.8 mm. Prolactin level was at 118.9 ng/mL, gonadotropins (FSH 5 mIU/mL, LH 4.3 IU/L) were within normal range for pre-menopausal non pregnant women and early 24h urine cortisol was within normal at 63.79 nmol/ day. Patient was started on propranolol 40 mg thrice daily and methimazole 20 mg twice a day which prompted slight relief. She was also referred to neurosurgery service for further management. Patient underwent transsphenoidal surgery which was tolerated well. Subsequent clinical course revealed improvement of hyperthyroid symptoms with no evidence of post-operative complications such as hematomas, CSF leak, vision loss, diabetes insipidus or central adrenal insufficiency. Immunohistochemical staining was positive for TSH. On outpatient follow-up, repeat thyroid function tests were within normal with TSH 1.260 and free T4 15.07 pmol/L. Patient is currently symptom free and off methimazole or propranolol. Future plans include a repeat MRI after 6 months of surgery and hormonal testing to confirm cure.

MON-288 TSH Deficiency in Patients on Somatostatin Analog for TSH-PitNET

Background: Somatostatin analogs (SSA) are efficiently used to control central hyperthyroidism in patients with thyrotropin-secreting pituitary neuroendocrine tumor (TSH-PitNET). The aim of this study was to describe the frequency of thyrotropin (TSH) deficiency under SSA in patients with TSH-PitNET. Methods: We retrospectively recruited patients presenting a central hyperthyroidism due to TSH-PitNET. Inclusion criteria were patients treated in first, second or third line by short or long-acting SSA, with central hyperthyroidism before SSA. Patients treated by radiotherapy or dopamine agonist were excluded. TSH deficiency was defined by either a low FT4 or low FT4 and FT3, associated with non-elevated TSH concentrations during SSA therapy. We analyzed the frequency of TSH deficiency and the characteristics of patients with or without TSH deficiency. Results: 46 patients were included in the study. SSA were used as the first-line therapy in 21 of 46 patients (46%). Central hyperthyroidism was controlled in 36 of 46 patients (78%). TSH deficiency appeared in 7 of 46 patients (15%), after a median time of 4 weeks (4–7) after the starting of SSA, and for a median duration of 3 months (2.5–3). The TSH deficiency occurred after 1 to 3 injections of long-acting SSA. There were no differences in terms of clinical and hormonal features and size of adenomas between patients with or without TSH deficiency. Conclusions: In patients with central hyperthyroidism due to TSH-PitNET, SSA can induce TSH deficiency. Thyrotropic function should be assessed before each injection of SSA in order to adapt the frequency of injection when control of thyrotoxicosis rather than tumor reduction is purpose of the treatment.

An FSH and TSH pituitary adenoma, presenting with precocious puberty and central hyperthyroidism

A 19-year-old woman with a history of isosexual precocious puberty and bilateral oophorectomy at age 10 years because of giant ovarian cysts, presents with headaches and mild symptoms and signs of hyperthyroidism. Hormonal evaluation revealed elevated FSH and LH levels in the postmenopausal range and free hyperthyroxinemia with an inappropriately normal TSH. Pituitary MRI showed a 2-cm macroadenoma with suprasellar extension. She underwent successful surgical resection of the pituitary tumor, which proved to be composed of two distinct populations of cells, each of them strongly immunoreactive for FSH and TSH, respectively. This mixed adenoma resulted in two different hormonal hypersecretion syndromes: the first one during childhood and consisting of central precocious puberty and ovarian hyperstimulation due to the excessive secretion of biologically active FSH and which was not investigated in detail and 10 years later, central hyperthyroidism due to inappropriate secretion of biologically active TSH. Although infrequent, two cases of isosexual central precocious puberty in girls due to biologically active FSH secreted by a pituitary adenoma have been previously reported in the literature. However, this is the first reported case of a mixed adenoma capable of secreting both, biologically active FSH and TSH. Learning points: Although functioning gonadotrophinomas are infrequent, they should be included in the differential diagnosis of isosexual central precocious puberty. Some functioning gonadotrophinomas are mixed adenomas, secreting other biologically active hormones besides FSH, such as TSH. Early recognition and appropriate treatment of these tumors by transsphenoidal surgery is crucial in order to avoid unnecessary therapeutic interventions that may irreversibly compromise gonadal function.

Thyrotropinomas

Thyrotropinomas are rare tumours, accounting for no more than 1% of all secreting or nonsecreting pituitary adenomas (1, 2). Since the prevalence of pituitary tumours in the general population is about 0.03%, 1–3 thyrotropinomas are expected to be seen per million people. The number of reported thyrotropinomas increased exponentially in the past years, as a consequence of the introduction of ultrasensitive immunometric assays for thyroid-stimulating hormone (TSH) as first-line test for evaluating thyroid function (1). Based on the finding of measurable serum TSH levels in the presence of elevated thyroid hormone concentrations, many patients previously thought to be affected with Graves’ disease or toxic nodular goitre could be correctly diagnosed as patients with central hyperthyroidism. In our opinion, this latter term is preferable to ‘inappropriate secretion of TSH’, as it more precisely reflects the pathophysiological events underlying such an unusual disorder, where the thyroid hormone negative feedback mechanism is clearly disrupted and TSH itself is responsible for the hyperstimulation of the thyroid gland and the consequent hypersecretion of thyroid hormones (Fig. 2.3.13.1). Central hyperthyroidism is mainly due to autonomous TSH hypersecretion from a thyrotropinoma. However, signs and symptoms of hyperthyroidism along with biochemical findings similar to those found in thyrotropinoma, may be recorded in the minority of patients with resistance to thyroid hormones (RTH) (3, 4). This form of RTH is called pituitary RTH (PRTH), as the resistance to thyroid hormone action appears more severe at the pituitary than at the peripheral tissue level (see Fig. 2.3.13.1). The clinical importance of these rare entities is based on the diagnostic and therapeutic challenges they present. Failure to recognize these different disorders may result in undesirable consequences, such as improper thyroid ablation in patients with central hyperthyroidism or unnecessary pituitary surgery in patients with RTH. Conversely, early diagnosis and correct treatment of thyrotropinomas may prevent the occurrence of complications (visual defects by compression of the optic chiasm, hypopituitarism, etc.) and should improve the rate of cure.