Critical Care Medicine

Thyroid Disorders: Complications of thyroid surgery

1. Description of the problem

What every clinician needs to know

Whenever possible, thyroid surgery should be performed by an experienced, high-volume surgeon to minimize complications.

Chronic complications include hypothyroidism (which is the expected result of most thyroid surgery) and hypoparathyroidism. In the hands of an experienced, high-volume surgeon, the incidence of acute complications and of permanent hypoparathyroidism should be less than 1%.

Thyroid operations (thyroidectomy) are used for patients who have a variety of thyroid conditions, including both malignant and benign thyroid nodules, large compressive goiters and overactive thyroid glands (both Graves’ disease and toxic nodular goiters). The acute complications of thyroid surgery include 1) hypocalcemia, 2) vocal cord motion abnormalities and 3) hematoma, all of which can be life threatening.

Clinical features

Vocal cord motion abnormalities

Coughing, dyspnea and hoarseness after thyroid surgery are all symptoms of vocal cord motion abnormalities. Patients with dyspnea and respiratory distress should be referred immediately for direct laryngoscopy. Transient recurrent laryngeal nerve paresis, either unilateral or bilateral, was observed in approximately 2.5% of patients in one series, while permanent nerve injury occurred in 1%. Bilateral nerve injury is usually apparent immediately after extubation with stridor and respiratory distress.

Hematoma

A cervical hematoma is characteristically a large, firm immobile swelling. Hematomas have been reported in up to 1.2% of thyroid operations.

Hypocalcemia

Damage to the parathyroid glands during surgery producing mild hypocalcemia is relatively common, with a reported incidence of up to 49%. Severe hypocalcemia and permanent hypoparathyroidism is much less frequent. Hypocalcemia is made worse by co-existing vitamin D deficiency.

Preoperative evaluation should include measurement of 25-hydroxyvitamin D (25OHD) levels and replacement if possible before surgery. Symptoms range from mild numbness and tingling to muscle twitching and cramping and, rarely, frank tetany and trismus. Electrocardiogram (ECG) changes can be seen with shortened Q-T intervals with the potential for arrhythmias.

Chyle fistulae

Reported in up to 8.3% of thyroid surgeries when a lateral neck dissection has been performed and are caused by injuries to the thoracic duct. Clues to detection are bulging in the supraclavicular fossa and induration or erythema of the skin. A milky discharge confirms the diagnosis.

Tracheal injury

Tracheal necrosis is rare and may be seen by overzealous use of the electrocautery around the trachea. Tracheomalacia can be seen in the setting of large, long-standing compressive goiters. Tracheal disruption leads to an air leak with subcutaneous emphysema, which is potentially life-threatening.

Esophageal injury

This rare complication can occur with symptoms of extensive crepitus throughout the surgical tissues.

Hypothyroidism

While not an acute complication of thyroid surgery, it is the expected result after a total or near-total thyroidectomy and frequently occurs after less complete surgeries. Since the half-life of thyroxine, the principal secretory product of the thyroid gland, is 7 days, symptomatic hypothyroidism would not present during the immediate postoperative period. If thyroid hormone replacement is not started postoperatively, typical symptoms of hypothyroidism would be expected within 4 weeks in patients that underwent a total or near-total thyroidectomy.

For those patients that undergo a subtotal thyroidectomy or a lobectomy, the remaining thyroid tissue may function sufficiently to meet the body's requirements.

Key management points

Most postoperative thyroidectomy patients should be observed overnight for hematoma formation and hypocalcemia. Serum calcium levels should be monitored frequently (every 8–12 hours) and with the development of any symptoms. The routine administration of calcium supplementation (1000 mg of elemental calcium 2–3 times daily) is reasonable and can be discontinued in the outpatient setting. If serum calcium levels drop below 7.2 mg/dL, calcitriol 0.25 to 0.5 mcg twice daily should be started.

Vocal cord motion abnormalities

Airway protection is essential and occasionally re-intubation is needed.

Hematoma

A significant hematoma needs to be surgically evacuated.

Hypocalcemia

The routine administration of calcium supplementation (1000 mg of elemental calcium 2–3 times daily) is reasonable and can be discontinued in the outpatient setting. If serum calcium levels drop below 7.2 mg/dL, calcitriol 0.25 to 0.5mcg twice daily should be started.

Chyle fistulae

Persistent fistulae need to be surgically repaired.

Tracheal injury

Airway protection is essential and occasionally re-intubation is needed. Rarely a tracheostomy may be required.

Esophageal injury

This rare complication usually needs to be surgically repaired.

Hypothyroidism

Since the half-life of thyroxine, the principal secretory product of the thyroid gland, is 7 days, symptomatic hypothyroidism would not present during the immediate postoperative period. Thyroid hormone replacement therapy (1,7 mcg/kg body weight) should be instituted in all patients that underwent a total or near-total thyroidectomy. For those patients who undergo a subtotal thyroidectomy or a lobectomy, the remaining thyroid tissue may function sufficiently to meet the body's requirements.

2. Emergency management

Vocal cord motion abnormalities

If possible, re-intubation should be performed. Inhaled racemic epinephrine, humidified air and oxygen and intravenous steroids.may be temporizing measures; rarely a tracheostomy is required. A tracheostomy tray needs to be at the patient's bedside for up to 24 hours postoperatively. Supportive care perioperatively is aimed to avoid aspiration. Vocal training/therapy may be needed for long-term management.

Hematoma

If a large hematoma develops, emergent surgical evacuation is required. Overnight intubation is recommended to allow supraglottic edema to resolve before extubation.

Hypocalcemia

Acute management includes intravenous calcium to relieve tetany and resolve ECG changes followed by oral calcium supplementation (1–3 g daily). Serum parathyroid hormone levels have been shown to be helpful, with parathyroid hormone (PTH) levels less than 15 ng/L predictive of significant hypocalcemia.

Mild hypocalcemia can be managed with oral calcium alone (1000 mg elemental calciuim 2–4 times daily), but patient's severe hypocalcemia (total calcium less than 7.2 mg/dL, ionized calcium less than 1 mmol/L) should also be treated with vitamin D (calcitriol 0.25–0.5mcg daily to BID).

Chyle fistulae

Surgical intervention may be needed for high output (greater than 500mL/d) from the fistulae. Large fluid shifts and electrolyte imbalances may be seen.

Tracheal injury

Surgical re-exploration is usually needed.

Esophageal injury

Surgical re-exploration is usually needed.

Hypothyroidism

If a total or near-total thyroidectomy was performed, levothyroxine (L-T4) replacement therapy should be started postoperatively at a daily dose of approximately 1.7mcg/kg orally. In the case of surgery for thyroid cancer in whom radioactive iodine therapy will be planned under hypothyroid conditions, liothyronine (L-T3) at a dose of 25mcg BID – TID can be started instead. If a subtotal thyroidectomy or lobectomy has been performed, the decision to start thyroid hormone replacement therapy can be deferred for 1 to 3 months to be determined if needed.

What's the evidence?

Gourin, CG, Johnson, JT, Randolph, G. "Postoperative complications". Surgery of the Thyroid and Parathyroid Glands. Saunders/Elsevier. August 2012.

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