Preoperative Management of Hypothyroid Patients on Levothyroxine

Medication Management

The American College of Cardiology recommends continuing levothyroxine on the morning of surgery without interruption, including the day of the procedure, to prevent perioperative complications 1
The National Comprehensive Cancer Network explicitly recommends continuing levothyroxine through the surgical period to maintain stable thyroid hormone levels and prevent worsening perioperative outcomes 1
No stress-dose adjustment is required for levothyroxine, unlike glucocorticoids, as it does not increase bleeding risk or interfere with anesthesia 2
Levothyroxine does not increase bleeding risk or interfere with anesthesia, making it safe to continue perioperatively 1

Delay elective surgery until euthyroidism is achieved whenever feasible to reduce perioperative risks 2
Hypothyroid patients undergoing surgery face specific complications, including increased risk of heart failure, gastrointestinal complications, and neuropsychiatric complications 3, 4, 5, 6
The American Heart Association recommends monitoring for signs of severe hypothyroidism, including lethargy, prolonged ventilation requirements, and hypotension, particularly in patients with coronary artery disease 3, 4, 5, 6

Rule out adrenal insufficiency before surgery, as hypothyroidism treatment is contraindicated until adrenal insufficiency is corrected 2
Avoid etomidate for induction when possible, as it suppresses cortisol production, and maintain high clinical suspicion for relative adrenal insufficiency throughout the perioperative period 2

Monitor for signs of severe hypothyroidism, including lethargy, prolonged ventilation requirements, and hypotension, and watch for gastrointestinal and neuropsychiatric complications 3, 4, 5, 6
The American Thyroid Association recommends resuming oral levothyroxine as soon as the patient can tolerate oral intake, and administering it as a single dose, preferably on an empty stomach, one-half to one hour before breakfast with a full glass of water 1

Do not hold levothyroxine perioperatively, as interruption destabilizes thyroid status and worsens surgical outcomes, according to the American College of Cardiology 1
Do not overlook subclinical hypothyroidism, as even patients with TSH between 4.5-10 mIU/L face increased perioperative risks, particularly cardiovascular complications, as reported by the American Heart Association 3, 4, 5, 6

Detect hypothyroidism at least 28 days before elective surgery to provide sufficient time for evaluation, optimization, and confirmation of euthyroidism; this timing recommendation originates from anemia‑related guidelines and should be adapted for thyroid management contexts 7