Background: Pituitary adenomas that produce thyroid-stimulating hormone (TSH) represent only 1% of functioning pituitary adenomas and commonly cause symptoms of hyperthyroidism of diffuse goiter.
No cases where found regarding a TSH secreting tumour surgery with elevated laboratory values and no symptoms of hyperthyroidism. 
Case report: We present a case of a 45-year-old male, proposed for endoscopic resection of pituitary adenoma with mass effect causing intense headaches. He was 188cm tall and weighed 107kg. He had a history of hypocortisolism and hyperthyroidism with altered laboratory values caused by the pituitary adenoma. The endocrinology department was contacted and reported that, despite having a TSH of 2.26mUI/mL (0.27-4.2) and a free thyroxine level (T4L) of 25.1pmol/L (12-22), the patient was asymptomatic without signs of thyroid hyperfunction and so, they would not contraindicate the surgery. Vital signs, chest X-rays, electrocardiogram, and other laboratory values were unremarkable. The case was managed with a remifentanil and propofol target-controlled infusion and rocuronium (0.6 mg/kg). Laryngoscopy and intubation were performed and he was ventilated to maintain a carbon dioxide pressure of 35-40 mmHg and heated to maintain a central temperature of 35-37°C. Immediately after induction, the patient began to show blood pressure (BP) instability with values that increased to 190/110mmHg. Esmolol infusion failed to normalize BP and only after the addition of an isosorbide dinitrate infusion did we control the patient's BP to values of 110/70mmHg.
Vital values were stable throughout the rest of the surgery. Postoperative nausea and vomiting prophylaxis with dexamethasone and ondansetron was given and postoperative analgesia was managed with paracetamol, metamizole and morphine. Corticosteroid supplementation was done with methylprednisolone. Propofol and remifentanil infusions were stopped, neuromuscular blockade reversed with sugammadex (2 mg/kg) and extubation occurred after full reversal of the blockade. He had an uneventful postoperative course with BP around 135/82mmHg and was discharged after 4 days. His biochemical values were normal at the time of discharge.
Discussion: Although rare, secretory pituitary adenomas can cause severe hemodynamic changes and be an anaesthetic challenge.
This case aims to alert the anaesthetic community to the risk of TSH secreting pituitary adenomas with hyperthyroidism even in asymptomatic patients.

References: 
Arnason, T., Clarke, D. B., & Imran, S. A. (2011). Hyperthyroidism caused by a pituitary adenoma. CMAJ : Canadian Medical Association Journal, 183(11), E757. http://doi.org/10.1503/cmaj.101244;
P. A. Farling; Thyroid disease, BJA: British Journal of Anaesthesia, Volume 85, Issue 1, 1 July 2000, Pages 15–28, https://doi.org/10.1093/bja/85.1.15.

07 / Asymptomatic hyperthyroidism in a thyroid-stimulating hormone secreting pituitary adenoma. An unexpected anaesthetic challenge: Case report