1. Perioperative Management of Thyroid Dysfunction
Tehran,
Perioperative Management of Thyroid Dysfunction
M. Nakhjavani, MD,
Department of Endocrinology and Metabolic Diseases
Vali-Asr Hospital
Tehran University of Medical Sciences

2. Perioperative Management of Thyroid Dysfunction Outline
Preoperative screening Hypothyroid patients Recommendations for hyperthyroid patients Rapid preparation of the thyrotoxic patient for surgery Thyroidectomy in thyroid storm patients Surgery in Nonthyroidal Illness

3. Perioperative Management of Thyroid Dysfunction
Prevalence of abnormal thyrotropin values to be as high as 21% in women and 3% in men. Routine preoperative thyroid function testing is not recommended for patients with no history of thyroid dysfunction It would be appropriate to check the thyrotropin (TSH) level if there is a reason to suspect thyroid disease based on symptoms such as unexplained weight changes, palpitations, tremor or changes in bowel habits, skin, hair, or eyes that suggest thyroid dysfunction.

4. Preoperative Screening
Recognition, diagnosis, and optimization of preexisting thyroid conditions in patients undergoing surgery are important perioperative considerations

5. Preoperative Screening
In patients with known hypothyroidism or hypothyroidism who have been undergoing treatment, a TSH test should be included in the preoperative assessment to determine the adequacy of treatment and to ensure that thyroid therapy is optimized before surgery.

6. Complications of Hypothyroidism
Increased risk of coronary events
Diminished cardiac output of 30% to 50%
Increased peripheral vascular resistance ,increased cardiac afterload
Decreased pulse pressure
Hypotension under anesthesia due to downregulation of β- adrenergic receptor
Ventilatory dysfunction

7. Complications of Hypothyroidism
Decreased renal perfusion leading to decreased clearance of medications
Hyponatremia
Decreased gastrointestinal motility
Anemia
Decrease in factor VIII activity, prolonged PTT and acquired von Willebrand disease
Myxedema coma

8. Preoperative Considerations in the Hypothyroid Patient
Pathophysiologic changes associated with hypothyroidism are generally reversible with replacement of thyroid hormone Postpone elective surgery until adequate treatment with thyroid hormone has achieved euthyroidism

9. Preoperative Considerations in the Hypothyroid Patient
Full replacement dose of levothyroxine is usually 1.6 μg/kg/day. In the elderly or those with known coronary artery disease, the initial dose is usually 25 μg daily With a planned increase, every 2 to 6 weeks Once TSH values normalize, surgery can be performed

10. Preoperative Considerations in the Hypothyroid Patient
The patient may miss the dose of levothyroxine on the day of surgery If oral medications cannot be given postoperatively, the dose may be missed for several days If there is still no ability to administer the drug enterally after 5 days, intravenous (IV) levothyroxine should be administered at a dose between 60% and 80% of the oral dose

11. Outcome of anesthesia and surgery in 59 hypothyroid patients compared with 50 euthyroid patients
 No differences in:
Duration of surgery or anesthesia
Lowest temperature and blood pressure
Need for vasopressors
Time to extubation, Need for postoperative respiratory assistance
Fluid and electrolyte imbalances
Incidence of arrhythmias
Pulmonary or myocardial infarction
Sepsis, Bleeding complications
Time to hospital discharge

12. Patients divided based on thyroxine level: < 1.0 μg/dL
Outcome of anesthesia and surgery in 59 hypothyroid patients compared with 50 euthyroid patients
Patients divided based on thyroxine level:
< 1.0 μg/dL
1 to <3.0 μg/dL,
> 3.0 μg/dL
There were no differences in outcomes

13. Outcome of anesthesia and surgery in 59 hypothyroid patients compared with 50 euthyroid patients
Because there were only 7 patients in the group with the lowest T4 concentration, the authors concluded that in mild to moderate hypothyroidism, there is no evidence to justify postponing surgery that is needed, but in severe hypothyroidism, there is insufficient evidence to make a recommendation
Weinberg AD, et al. Outcome of anesthesia and surgery in hypothyroid patients.
Arch Intern Med.1983;143:893–897.

14. No increase in major adverse cardiovascular events Wound problems
Outcome of anesthesia and surgery in 59 hypothyroid patients compared with 50 euthyroid patients
No increase in major adverse cardiovascular events
Wound problems
Mediastinitis
Leg infection
Respiratory complications,
Delirium, or reoperation during the same hospitalization .

15. Comparing postoperative outcomes in patients with subclinical hypothyroidism to euthyroid patients undergoing Coronary Artery Bypass Grafting (CABG)
There was an increase in the rate of postoperative atrial fibrillation in the subclinical hypothyroidism group
Park YJ, et al. Subclinical hypothyroidism might increase the risk of transient atrial fibrillation after coronary artery bypass grafting. Ann Thorac Surg. 2009;87:1846–1852

16. Complications of surgery in hypothyroid patients: A retrospective study
40 hypothyroid surgical patients, most of whom had mild to moderate severe hypothyroidism, were compared with 80 euthyroid surgical patients
Among those undergoing noncardiac surgery, intraoperative hypotension occurred at a higher rate in
the hypothyroid group
Ladenson PW,, et al. Am J Med. 1984;77:261–266.

17. For those undergoing cardiac surgery,
Complications of surgery in hypothyroid patients: A retrospective study
40 hypothyroid surgical patients, most of whom had mild to moderate severe hypothyroidism, were compared with 80 euthyroid surgical patients
For those undergoing cardiac surgery,
the development of heart failure was more prevalent in the
hypothyroid group
Ladenson PW,, et al. Am J Med. 1984;77:261–266.

18. Complications of surgery in hypothyroid patients: A retrospective study
No differences in:
Rate of postoperative infection
Perioperative blood loss, Duration of hospitalization
Rates of arrhythmia, Hypothermia, Hyponatremia
Delayed recovery from anesthesia
Tissue integrity, Wound healing, Pulmonary complications,
or Death 
Ladenson PW,, et al. Am J Med. 1984;77:261–266.

19. Ladenson PW,, et al. Am J Med. 1984;77:261–266.
Complications of surgery in hypothyroid patients: A retrospective study
Applicability of conclusions drawn from these data may be limited as only 2 of the patients studied were categorized as having severe hypothyroidism
Ladenson PW,, et al. Am J Med. 1984;77:261–266.

20. Recommendations for Hypothyroid Patients
 Definitions of mild, moderate, and severe hypothyroidism
Subject to interpretation Vary between studies Number of studies is quite limited

21. Recommendations for Hypothyroid Patients
Elective surgery to be postponed until a euthyroid state is achieved.
Mild or moderate hypothyroidism in patients requiring urgent or emergent surgery :
Levothyroxine should be started preoperatively
 There should be increased awareness of the possibility of
minor postoperative complications

22. Recommendations for Hypothyroid Patients
Classification of “severely hypothyroid”
Patients with myxedema coma Altered mentation Pericardial effusions or heart failure Very low levels of thyroxine (<1 μg/dL)

23. Recommendations for Hypothyroid Patients
Severely hypothyroid :
Nonemergent surgery :
Should be postponed until the hypothyroidism has been treated
Lack of outcome data, understanding of the risks
Emergent surgery :
Thyroid hormone levels should be normalized rapidly, IV levothyroxine in a loading dose of 200 to 500 μg followed by 50 to 100 μg IV daily.
Administration of IV liothyronine should be considered if there is suspicion for myxedema coma.
If there is any suspicion for concurrent adrenal insufficiency, glucocorticoids should be administered in stress doses prior to or together with thyroid hormone.

24. Recommendations for Hypothyroid Patients
Cardiac revascularization
Patients who require cardiac revascularization are the only subset of patients who may not benefit from preoperative replacement of thyroid hormone
In patients with angina, there is possibility of worsening cardiac ischemia by replacing thyroid hormone and consequently increasing myocardial oxygen demand.
Drucker DJ, et al. Cardiovascular surgery in the hypothyroid patient.
Arch Intern Med. 1985; 145:1585–1587.
Myerowitz PD, et al. Diagnosis and management of the hypothyroid patient with chest pain. J Thorac Cardiovasc Surg. 1983; 86:57–60.

25. Complications of Hyperthyroidism: Most salient features
Positive ionotropic chronotropic effects on the heart
Vasodilation and decrease in systemic vascular resistance
Consequent increase in sodium and water retention
mediated by the renin-angiotensin-aldosterone system
An increase in cardiac output by 50% to 300%
Atrial fibrillation occurs in 10% to 15% of patients
The prevalence of atrial fibrillation increases with age

26. Optimization of Cardiovascular Status Before Surgery in Hyperthyroid Patients
No published studies evaluating the perioperative outcomes of hyperthyroid patients compared with euthyroid patients Risk of precipitating thyroid storm Elective surgeries should always be postponed in patients with overt hyperthyroidism

27. Optimization of Cardiovascular Status Before Surgery in Hyperthyroid Patients
In those with mild or subclinical disease, preoperative β - blockade is considered sufficient

28. Optimization of Cardiovascular Status Before Surgery in Hyperthyroid Patients
This is supported by a prospective randomized trial showing that in hyperthyroid patients undergoing thyroidectomy who were treated with just 5 weeks of metoprolol preoperatively, there were no serious intra- or postoperative complications, compared with patients who were pretreated for 12 weeks with a combination of methimazole and levothyroxine to render them euthyroid.
Alderbeith A, et al. The selective beta 1-blocking agent metoprolol compared with antithyroid drug and thyroxine as preoperative treatment of patients with hyperthyroidism. Results from a prospective, randomized study.
Ann Surg. 1987; 205:182–188

29. Optimization of Cardiovascular Status Before Surgery in Hyperthyroid Patients

30. Overt hyperthyroidism requiring urgent or emergent surgery
Perioperative placement of an arterial line or central venous pressure monitor if the patient is not hemodynamically stable Optimization of cardiac status β -blockers

31. Rapid Preparation of the Thyrotoxic Patient for Surgery
Drug Class
Recommended
Drug
Dose
Mechanism of Action
Continue
Postoperatively?
Beta-adrenergic
blockade
Propranolol
40–80 mg po tid-qid
Beta-adrenergic blockade;
decreased T4 to T3
conversion (high dose)
Yes
Esmolol
50–100 μg/kg/min
Change to oral propranolol

32. Overt hyperthyroidism requiring urgent or emergent surgery
No particular β -blocker has established superiority over others Atenelol a beta-1-selective agent may be tolerated better in patients with reactive airway disease

33. Overt hyperthyroidism requiring urgent or emergent surgery
Beta-blocker: Atenelol
Metabolism accelerated in thyrotoxicosis Initial dose 25 mg daily Higher doses, 50 mg up to more than 200 mg daily, may be required

34. Overt hyperthyroidism requiring urgent or emergent surgery
Propranolol
A nonselective beta-1 and beta-2- blocker Shorter half-life necessitating the administration of multiple daily Inhibits the monodeiodinase type I enzyme Can be used intravenously to control pulse and blood pressure Decrease fever intraoperatively

35. Overt hyperthyroidism requiring urgent or emergent surgery
Calcium channel blockers
In patients who cannot tolerate β –blockers Should be titrated to achieve a heart rate under 80 beats per minute

36. Overt hyperthyroidism requiring urgent or emergent surgery
Reserpine and guanethidine
Decrease sympathetic activity
Reserpine and guanethidine may be considered for those
in whom β -blockers and calcium channel blockers are contraindicated
Burch HB, Wartofsky L. Life-threatening thyrotoxicosis. Thyroid storm.
Endocrinol Metab Clin North Am. 1993;22:263–277.

37. Rapid Preparation of the Thyrotoxic Patient for Surgery
Drug Class
Recommended
Drug
Dose
Mechanism of Action
Continue
Postoperatively?
Thionamide
Propylthiouracil
200 mg po q 4 h
Inhibition of new thyroid
hormone synthesis;
decreased T4 to T3
conversion
Stop immediately after
near total thyroidectomy;
continue after
nonthyroidal surgery
Methimazole
(carbimazole)
20 mg po q 4 h
 Inhibition of new thyroid
hormone synthesis

38. MMI and PTU

39. Rapid Preparation of the Thyrotoxic Patient for Surgery
Drug Class
Recommended
Drug
Dose
Mechanism of Action
Continue
Postoperatively?
Iodine
SSKI
2 drops q 8 h
Inhibition of new thyroid
hormone synthesis;
decreased release of thyroid
hormone No
Lugol’s
3–5 drops q 8 h

40. Urgent need to stabilize the thyrotoxicosis
Inorganic iodide: Wolff-Chaikoff effect
Inorganic iodide as an adjunct to thionamides
Blocks the organification of iodine
Decreasing the synthesis of thyroid hormones
Transient phenomenon
Apparent within 24 hours
Escape from the Wolff-Chaikoff effect is anticipated to occur after approximately 10 days
Treatment with iodine should not be started more than10 days preoperatively
Wolff J, Chaikoff IL. The inhibitory action of excessive iodide upon the synthesis of diiodotyrosine and of thyroxine in the thyroid gland of the normal rat. Endocrinology. 1948; 43:174–179.

41. Urgent need to stabilize the thyrotoxicosis
Inorganic iodide
Administered orally, rectally, or intravenously.
1 drop 3 times daily of saturated solution of potassium iodide
Or 3 to 5 drops of Lugol’s solution thrice daily

42. Urgent need to stabilize the thyrotoxicosis
Iopanoic acid
 An iodine-containing product
Administered in a dose of 500 mg twice daily
Reduces triiodothyronine levels even faster than the other
iodine preparations
Langley RW, et al. Perioperative management of the thyrotoxic patient.
Endocrinol Metab Clin North Am. 2003; 32:519–534.

43. Rapid Preparation of the Thyrotoxic Patient for Surgery
Drug Class
Recommended
Drug
Dose
Mechanism of Action
Continue
Postoperatively?
Corticosteroid
Dexamethasone
2 mg po or IV q 6 h
Vasomotor stability;
decreased T4 to T3
Taper over first 72 h
Hydrocortisone
100 mg po or IV q 8 h

44. Rapid Preparation of the Thyrotoxic Patient for Surgery
Drug Class
Recommended
Drug
Dose
Mechanism of Action
Continue
Postoperatively?
Resin agents
Cholestyramine
4 g po q 6 h
Interference with
enterohepatic circulation
Stop immediately
postoperatively

45. Preoperative Preparation of Hyperthyroid Patient
Those undergoing thyroidectomies for the Graves should be:
Rendered euthyroid prior to the procedure
With ATD pretreatment
With or without β -adrenergic blockade
Potassium iodide should be given in the immediate
preoperative period
  Ross DS, et al American Thyroid Association
Guidelines for Diagnosis and Management of Hyperthyroidism and other Causes of
Thyrotoxicosis. Thyroid. 2016;26:1343–1421

46. Rapid preoperative preparation of Hyperthyroid Patient
Need for urgent or emergent surgery
Insufficient time to be rendered euthyroid by thionamides before surgery Contraindications to thionamides use

47. Rapid preoperative preparation of Hyperthyroid Patient
Need for urgent or emergent surgery
Oral therapy with a combination of beta blocker high- dose glucocorticoids, and cholcystographic agent (iopanoate) for 5 days with surgery performed on the sixth day Baeza A, et al. Rapid preoperative preparation in hyperthyroidism. Clinical Endocrin. 1991;35:439–442.

48. Emergent preparation for thyroid surgery
  Thyrotoxic patients unable to use or responding poorly to antithyroid drugs
 • Propranolol 60 mg orally, twice daily
 • Dexamethasone 2 mg intravenously,
four times daily
 • Cholestyramine 4 g orally, four times daily
 • SSKI 2 drops orally, three times daily
Given for 5–10 days before thyroidectomy
Langley RW, Burch HB. Perioperative management of the thyrotoxic patient. Endocrinol Metab Clin
North Am. 2003;32:519–534.

49. Thyroidectomy in thyroid storm patients
39 cases from the literature
10 additional cases from author’s center,
Tthyroidectomy ultimately used
to treat thyroid storm.
Early or late postoperative mortality was reported in 5 of 49 (10.2%) patients
Scholz GH, , et al. Is there a place for thyroidectomy in older patients with
thyrotoxic storm and cardiorespiratory failure?
Thyroid. 2003;13:933–940

50. Thyroid Storm: Therapy directed against the thyroid gland
Blockade of iodine organification is established within an hour of administration of any of the ATDs PTU has the advantage over MMI of decreasing the conversion of T4 to T3 Because of this unique property, thyroid storm continues to be one of a few conditions in which PTU is used preferentially over the more potent MMI

51. Thyroid Storm: Therapy directed against the thyroid gland
Iodine therapy should not be initiated until a blockade of new thyroid hormone synthesis has been established with thionamide antithyroid drugs (approximately 1 hr)
“Unprotected” use of iodine will complicate:
Any planned management by delaying the effectiveness of antithyroid drug therapy, increasing surgical risk due to an enrichment of glandular hormone stores,
Postponing radioiodine ablation
pending clearance of the iodine load  

52. Non-oral administration of antithyroid drugs
Intravenous methimazole by reconstituting 500 mg of methimazole powder in 0.9% sodium chloride solution to a final volume of 50 mL. The resulting solution of 10 mg/mL was then filtered through a 0.22-mm filter and administered as a slow intravenous push over 2 minutes, followed
by a saline flush. Standard sterile pharmacological techniques are obviously required in the preparation process for these alternate medical vehicles.
Hodak SP, et al. Intravenous methimazole in the treatment of refractory hyperthyroidism.
Thyroid. 2006;16:691–695.

53. in 12 mL of water with two drops of
      Non-oral administration of antithyroid drugs Rectal administration of antithyroid drugs  
Preparation of a suppository consisting of 1,200 mg of methimazole dissolved
in 12 mL of water with two drops of
Span 80 (a nonionic surfactant), mixed with 52 mL of cocoa butter, has
been described  
Nabil N, et al. Methimazole: an alternative route of administration. J Clin Endocrinol Metab. 1982;54:180–181.

54. Thyroid Surgery ENT examination
Indirect laryngoscopy should preferably be carried out by an ENT specialist as 3-5% of population invariably has unilateral paralysis of vocal cords
Chin SC, et al. Using CT to localize side and level of vocal cord paralysis.
AJR Am J Roentgenol 2003;180:1165‑70.

55. Non thyroidal Illness
When thyroid dysfunction is suspected in critically ill patients, measurement of serum TSH alone is not enough for diagnosis of thyroid dysfunction. Instead, measurement of TSH, total T4, free T4, T3, and sometimes reverse T3 is necessary

56. Nonthyroidal Illness
If the diagnosis of hypothyroidism is in doubt in a critically ill patient and surgery cannot be postponed, treat with thyroid hormone replacement if there is clinical evidence to suggest a diagnosis of hypothyroidism

57. Nonthyroidal Illness
In the absence of suspected myxedema coma, repletion should be cautious, beginning with approximately half the expected full replacement dose of T4