What is involved in a thyroidectomy procedure?

Thyroidectomy: Procedure Overview

Thyroidectomy involves surgical removal of all or part of the thyroid gland, with the extent of resection (total vs. hemithyroidectomy) determined by the underlying pathology, tumor characteristics, and risk stratification.

Preoperative Assessment

Essential preoperative workup includes:

• Neck ultrasound to assess tumor extension, invasion, and lymph node status 1
• Fine needle aspiration cytology (FNAC) for tissue diagnosis, with molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) when cytology is indeterminate 1
• Serum calcitonin measurement to screen for medullary thyroid cancer 1
• CT imaging of the neck to determine extent of tumor and identify invasion of great vessels and upper aerodigestive tract structures 1
• Thyroid function tests (TSH, FT3, FT4) 1

Surgical Extent: Decision Algorithm

For Papillary Microcarcinoma (≤10 mm)

Hemithyroidectomy (lobectomy) is appropriate when ALL of the following criteria are met:

• Unifocal tumor ≤10 mm 1, 2
• No extracapsular or extrathyroidal extension 1, 2
• No lymph node metastases (N0) 1, 2
• No history of head/neck radiation 1

Active surveillance (ultrasound every 6-12 months) is an alternative to immediate surgery for these same patients, particularly those >40 years old 1, 2

For Low-Risk Tumors (T1a-T1b-T2, N0)

Hemithyroidectomy may be extended to selected tumors up to 2 cm (T1b) without extrathyroidal extension or lymph node involvement 1, 2. However, this approach may be associated with slightly higher local recurrence rates compared to total thyroidectomy 1.

For All Other Thyroid Cancers

Total or near-total thyroidectomy is the standard surgical treatment when:

• Tumor >2 cm 1
• Multifocal disease 1
• Extrathyroidal extension present 1
• Lymph node metastases documented 1
• Follicular cancer (except minimally invasive) 1
• Medullary thyroid cancer 1
• Anaplastic thyroid cancer (if resectable) 1

Lymph Node Management

Central neck dissection (level VI) indications:

• Mandatory for medullary thyroid cancer with no evidence of lymph node metastases 1
• Consider for more invasive tumors (T3-T4) to improve regional control 1
• Controversial for low-risk tumors (T1b-T2, N0) - allows accurate staging but increases hypoparathyroidism risk without proven survival benefit 1

Lateral neck dissection (levels II-V) is indicated when:

• Preoperative imaging shows lateral lymph node metastases 1
• Intraoperatively proven lymph node metastases 1
• Primary tumor ≥1 cm with central compartment lymph node metastases 1

Surgical Technique Considerations

Critical structures requiring identification and preservation:

• Recurrent laryngeal nerves bilaterally 1
• All four parathyroid glands with their blood supply 1
• Superior laryngeal nerves 3

For medullary thyroid cancer with concurrent hyperparathyroidism (MEN 2A):

• Leave or autotransplant the equivalent mass of one normal parathyroid gland 1
• Consider cryopreservation of resected parathyroid tissue for future implantation 1

Postoperative Complications

Hypoparathyroidism

Temporary hypocalcemia occurs in 5.4-12% of patients after total thyroidectomy, with permanent hypoparathyroidism in 1.1-2.6% 1, 4. The risk is approximately twice that of hemithyroidectomy 1.

Clinical presentation:

• Perioral numbness and peripheral tingling are pathognomonic 4
• Muscle cramps and carpopedal spasm 4

Management:

• Immediate serum calcium measurement with monitoring every 6-8 hours until stable 4
• Calcium plus vitamin D supplementation for at least 10 days 3

Recurrent Laryngeal Nerve Injury

Permanent injury occurs in 2.5-3.4% after total thyroidectomy vs. 1.9% after subtotal thyroidectomy 1. Temporary palsy affects 5-11% of patients 3.

Clinical presentation:

• Voice changes, hoarseness, and dysphonia 4
• Vocal fold immobility 4
• NOT perioral numbness or limb tingling 4

Management:

• No invasive therapy for at least 6 months as most cases recover 3
• Laryngeal surgery techniques may be considered if sequelae persist beyond 6 months 3

Postoperative Hemorrhage

Occurs in 1.0-1.9% of cases, requiring immediate reoperation 1, 5, 6.

Surgeon Experience Impact

Complication rates are significantly lower with high-volume surgeons:

• Surgeons performing >100 thyroidectomies/year: 4.3% overall complication rate 1
• Surgeons performing <10 thyroidectomies/year: 4 times higher complication rate 1

This volume-outcome relationship is critical when considering outpatient thyroidectomy, which is safe only in the hands of experienced surgeons 7.

Postoperative Management

Thyroid Hormone Replacement

After total thyroidectomy:

• Levothyroxine initiated immediately 1
• For high-risk differentiated thyroid cancer: TSH suppression to <0.1 μIU/ml 1, 2
• For low-risk disease: TSH maintained in normal range (0.5-2.0 μIU/ml) 1, 2
• For medullary thyroid cancer: TSH maintained within normal range (no suppression needed) 1

After hemithyroidectomy:

• Levothyroxine to maintain TSH in normal range (not suppressed) 2

Radioactive Iodine (RAI) Considerations

RAI is indicated:

• High-risk differentiated thyroid cancer patients 1

RAI is NOT indicated:

• Low-risk patients 1
• After hemithyroidectomy for papillary microcarcinoma 2
• Small (≤1 cm) intrathyroidal tumors with no locoregional metastases 2

For intermediate-risk patients, the decision must be individualized 1.

Follow-up Surveillance

After total thyroidectomy (2-3 months post-surgery):

• Thyroid function tests to verify adequate TSH suppression 1
• Physical examination 1
• Neck ultrasound 1
• Serum thyroglobulin measurement (basal and rhTSH-stimulated) 1

After hemithyroidectomy:

• Serial neck ultrasound annually is the primary surveillance tool 2
• Thyroglobulin measurements have limited utility due to remaining thyroid tissue 2

Special Considerations for Anaplastic Thyroid Cancer

Anaplastic thyroid cancer has a median survival of 4-5 months with no curative therapy 1. Most patients present with unresectable or metastatic disease 1.

Surgical approach:

• Total thyroidectomy with complete gross tumor resection attempted only if disease appears resectable 1
• Incomplete palliative resection (R2) or "debulking" is NOT recommended 1
• Tracheostomy may be needed for airway management but has significant QOL impact 1

Multimodal therapy (surgery + EBRT ≥40 Gy + chemotherapy) significantly improves outcomes for stage IVB disease but should be reserved for carefully selected patients 1.