- Symptoms of hyperthyroidism include tachycardia, fatigue, weight loss, nervousness, and tremor; patients with Graves' disease may also exhibit exophthalmos and infiltrative dermopathy (pretibial myxedema).
- In subclinical hyperthyroidism (TSH suppressed (< 0.4 mU/l) normal fT4/fT3, no or mild symptoms), routine preoperative treatment is not necessary unless a major high-risk surgery is planned.
However, if TSH < 0.01, symptoms, or planned cardiac or thoracic surgery, preoperative shielding with β-blockers and/or low-dose thiamazole (5 – 10 mg/d) and possibly an endocrinological evaluation is advisable.
- In overt hyperthyroidism, preoperative medical management is mandatory. Surgery in overt hyperthyroidism increases the risk of an intraoperative thyrotoxic crisis and is contraindicated. The following goals should be pursued:
- Achieving a euthyroid state (normal fT4/fT3) by inhibiting hormone synthesis with thiamazole (or in certain cases propylthiouracil during pregnancy or side effects of thiamazole).
- Preventing a thyrotoxic crisis through early and consistent treatment of hyperthyroidism. Before elective thyroid surgery, the patient must be euthyroid. Thiamazole + iodine + β-blocker combination a few days before surgery see below. Avoiding triggering factors such as infections, stress, and contrast agent administration.
- Cardiovascular stability (HR < 90/min), adrenergic symptoms can be mitigated with beta-blockers.
- Reduction of thyroid vascularization for surgery and short-term inhibition of hormone release by preoperative administration of inorganic iodine (usually potassium iodide or Lugol's solution).
The following regimen can be applied 4 - 6 weeks before surgery:
| 4 – 6 weeks before surgery | Start of thyrostatic therapy | Thiamazole (alternatively carbimazole, propylthiouracil) | e.g., 20 – 40 mg/day orally, depending on the severity of hyperthyroidism | |
from day 1 | β-blocker for heart rate control | Propranolol | 20 – 40 mg orally every 6 – 8 hours, target: HR < 90/min | |
| Last 5 – 7 days | Iodine blockade | Lugol's solution | 5 – 10 drops (equivalent to 50 – 100 mg iodine) 3 times/day, orally |
A thyrotoxic crisis - as a result of untreated or inadequately treated severe hyperthyroidism - is a life-threatening emergency that is accompanied by severe symptoms of hyperthyroidism and can lead to cardiovascular collapse or shock; it is treated with a range of antithyroid medications, iodine, beta-blockers, corticosteroids, and hemodynamic support.
The following regimen can be applied:
Optional regimen for acute treatment in thyrotoxic crisis
| Thyrostatic therapy | Propylthiouracil | 600 – 1000 mg initial orally or via nasogastric tube |
β-blockade | Propranolol | 1 – 2 mg intravenously, repeatable every 4 hours |
Iodine block | Lugol's solution | 1 hour after propylthiouracil administration: 5 drops every 8 hours |
Steroids | Hydrocortisone | 100 mg intravenously every 8 hours |
| Supportive | Antipyretics, fluids, cooling | inpatient-intensive care required |