For an adult (≥18 years) with normal cardiac function and no severe comorbidities, what are the indications, pre‑operative evaluation, appropriate surgical approach, and postoperative management for thyroid surgery?

Thyroid Surgery: Comprehensive Management Guide

Indications for Thyroid Surgery

Thyroid surgery is indicated for malignancy (confirmed or suspected), compressive symptoms (dyspnea, orthopnea, dysphagia), toxic goiter unresponsive to medical management, or cosmetic concerns in the setting of significant thyromegaly. 1

Malignant Disease Indications

• Total thyroidectomy is mandatory for: tumor >4 cm diameter, extrathyroidal extension, cervical lymph node metastases, distant metastases, poorly differentiated histology, aggressive variants (tall cell, columnar cell), bilateral disease, macroscopic multifocal disease, or prior radiation exposure 2, 3
• Medullary thyroid carcinoma ≥1 cm requires total thyroidectomy with bilateral central neck dissection (level VI), as regional nodal metastases are present in >50% at diagnosis 1, 2
• Hereditary MTC syndromes (MEN 2A/2B) require prophylactic total thyroidectomy at specific ages based on RET mutation risk level 2

Benign Disease Indications

• Compressive symptoms (dyspnea, orthopnea, dysphagia) are more commonly associated with substernal goiters and represent clear surgical indications 4
• Toxic multinodular goiter after failure of medical management 5, 6
• Bilateral thyroid nodules, particularly with history of head/neck radiation 7
• Follicular neoplasm on fine needle aspiration (requires surgical excision for definitive diagnosis) 8, 7

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Preoperative Evaluation

Voice and Laryngeal Assessment

All patients must undergo documented voice assessment once surgery is planned, and vocal fold mobility examination is required for patients with voice impairment, thyroid cancer with suspected extrathyroidal extension, or prior neck surgery. 1

• Document baseline voice quality in all patients to distinguish postoperative changes from preexisting abnormalities 1
• Examine vocal fold mobility (via flexible laryngoscopy, rigid laryngoscopy, or mirror examination) if: 1
  • Patient has voice impairment
  • Thyroid cancer with suspected extrathyroidal extension
  • Prior neck surgery (carotid endarterectomy, anterior cervical spine approach, cervical esophagectomy, prior thyroid/parathyroid surgery)
• Preoperative vocal fold paralysis strongly suggests invasive thyroid malignancy (>70% rate in invasive disease vs 0.3% in noninvasive disease) and necessitates modified surgical planning 1

Medullary Thyroid Carcinoma Workup

• Measure basal serum calcitonin, CEA, calcium, and plasma metanephrines/normetanephrines (or 24-hour urine collection) to identify comorbid pheochromocytoma and hyperparathyroidism in hereditary forms 1
• Neck ultrasound in all patients; add chest CT, neck CT, and three-phase contrast-enhanced liver CT/MRI if lymph node metastases documented or serum calcitonin >400 pg/ml 1

Anesthesia Considerations

• Inform anesthesiologist of abnormal preoperative laryngeal findings to avoid intubation trauma 1
• For massive goiters with airway compression, careful planning of intubation type and close collaboration between surgical and anesthesia teams is essential 4
• Avoid paralytic agents when intraoperative nerve monitoring is planned 1

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Surgical Approach

Extent of Surgery

The surgeon must identify the recurrent laryngeal nerve(s) during all thyroid surgery—this is a strong recommendation. 1

Total Thyroidectomy Indications

• Any malignant disease with high-risk features (see above) 2, 3
• Bilateral thyroid nodules 7
• Toxic multinodular goiter (preferred treatment for prompt control and goiter removal) 5
• History of head/neck radiation with thyroid nodule 7
• Medullary thyroid carcinoma ≥1 cm 1, 2

Lobectomy Acceptable When

• Unifocal papillary thyroid carcinoma ≤4 cm with no extrathyroidal extension, no lymph node metastases, no distant metastases, no prior radiation, and well-differentiated histology 2, 3
• However, total thyroidectomy remains the most common choice even when lobectomy is technically acceptable 2

Nerve Preservation

Take deliberate steps to preserve the external branch of the superior laryngeal nerve(s) during thyroid surgery. 1

• Identification of the recurrent laryngeal nerve is mandatory to minimize injury risk 1
• Laryngeal electromyography monitoring may be used during surgery (optional) 1
• Temporary recurrent laryngeal nerve injury occurs in ~10% of patients; permanent injury in 1-4% 1

Lymph Node Management

• For medullary thyroid carcinoma with no evidence of lymph node metastases: bilateral prophylactic central lymph node dissection (level VI) 1
• Lateral neck dissection (levels IIA, III, IV, V) reserved for patients with positive preoperative imaging 1
• For papillary thyroid carcinoma: prophylactic central neck dissection not mandatory in clinically node-negative cases, but therapeutic dissection performed if suspicious nodes identified intraoperatively 3

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Postoperative Management

Immediate Postoperative Period

Monitor for bleeding, airway distress, recurrent laryngeal nerve injury, and hypocalcemia—the four major complications of thyroid surgery. 4

• Postoperative hemorrhage requiring reoperation occurs in ~2% of cases 7
• Early postoperative hypocalcemia (≤8.0 mg/dL) occurs in ~8.5% of patients but permanent hypoparathyroidism is rare (0-3%) with experienced surgeons 7
• Document whether voice change has occurred postoperatively 1

Voice Rehabilitation

• Examine vocal fold mobility postoperatively if voice impairment develops 1
• Refer patients with abnormal vocal fold mobility to voice rehabilitation options 1

Thyroid Hormone Therapy

Initiate levothyroxine immediately after surgery with dual purpose: hormone replacement and TSH suppression (for malignant disease). 1

For Differentiated Thyroid Cancer

• High-risk patients: maintain TSH <0.1 mU/L to decrease progression of metastatic disease and reduce cancer-related mortality 1
• Low-risk patients: target TSH to lower part of normal range (no substantial benefit from aggressive suppression) 1
• Patients free of disease after initial treatment: shift from suppressive to replacement therapy 1

For Medullary Thyroid Cancer

• Maintain TSH within normal range (replacement therapy only, as TSH suppression provides no benefit) 1

For Benign Disease

• Standard replacement therapy to maintain euthyroid state 7

Surveillance for Differentiated Thyroid Cancer

• Measure thyroglobulin at 6-12 weeks postoperatively to establish baseline 2
• At 6-12 months: physical examination, neck ultrasound, basal and rhTSH-stimulated serum thyroglobulin measurement with or without diagnostic whole-body scan 1
• Subsequent follow-up: physical examination, basal serum thyroglobulin on levothyroxine therapy, and neck ultrasound annually 1

Surveillance for Medullary Thyroid Cancer

• Serum calcitonin (and CEA in specific cases) measurements are paramount for detecting persistent/recurrent disease 1
• Undetectable basal serum calcitonin after provocative testing (pentagastrin or calcium) strongly predicts complete remission 1
• If complete remission: repeat serum calcitonin every 6 months for 2-3 years, then annually 1
• Patients with biochemical remission have only 3% recurrence risk during long-term follow-up 1

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Critical Pitfalls to Avoid

• Never perform thyroid surgery without identifying the recurrent laryngeal nerve 1
• Do not proceed with lobectomy if preoperative ultrasound reveals suspicious cervical lymph nodes, patient has radiation history, or aggressive histologic variants are suspected 3
• Total thyroidectomy should only be performed by surgeons experienced in endocrine surgery to minimize hypoparathyroidism and nerve injury rates 2
• Do not assume normal voice equals normal vocal fold function—baseline laryngeal examination is needed in high-risk patients even with normal voice 1
• Inform anesthesiologist of abnormal laryngeal findings to prevent intubation-related trauma 1