Parathyroid Surgery

The parathyroid glands are four very small structures, about the size of a lentil, located behind or around the thyroid gland. Their main function is to regulate blood calcium levels through parathyroid hormone (PTH).

When one or more parathyroid glands produce excessive PTH (hyperparathyroidism), blood calcium rises (hypercalcemia). This can affect multiple systems: bones, kidneys, muscles, the nervous system, and digestion.

Parathyroid surgery can be challenging due to their small size, their anatomical variability (they are not in the same location in everyone), and their close relationship with complex cervical structures such as nerves and blood vessels.

Types of hyperparathyroidism

Hyperparathyroidism is divided into primary, secondary, and tertiary forms, each with different pathophysiological mechanisms.

Common indications:

A) Primary hyperparathyroidism (PHPT)
It occurs when one or more parathyroid glands become autonomous, producing PTH without control and raising blood calcium levels.

The four main causes are:

1. Parathyroid adenoma – 85%
A single gland (“adenoma”) causes the disease.
It is a benign tumor that grows and secretes excess PTH.
Treatment consists of removing that gland.

2. Multiglandular hyperplasia – 10–12%
All four glands are enlarged and overactive.
It may be sporadic or associated with MEN 1 / MEN 2A syndromes.
Treatment consists of removing 3 and a half glands, leaving half a gland functioning.

3. Multiple adenomas – 2–4%
Usually two glands are affected, with intermediate behavior.
The two diseased glands are removed, preserving the others with adequate function.

4. Parathyroid carcinoma – <1%
Extremely rare. It is characterized by:
- Very high calcium
- A palpable mass
- Markedly elevated PTH
It requires en bloc removal of the gland and any adjacent tissues involved or infiltrated.

Indications for surgery
Surgery is indicated when primary hyperparathyroidism is present with any of the following criteria:

  • Serum calcium >1 mg/dL above the normal value
  • Osteoporosis or T-score ≤ –2.5
  • History of fragility fractures
  • Kidney stones or nephrocalcinosis
  • Reduced glomerular filtration rate (<60 ml/min)
  • Marked hypercalciuria
  • Age <50 years (even if the patient is asymptomatic — AAES / 5th Workshop criterion)
  • Symptoms attributed to the disease: fatigue, bone pain, weakness, cognitive or mood changes, gastritis, arrhythmias
  • Patients who want definitive treatment through surgery

Surgery is the only curative treatment for primary HPT.



B) Secondary hyperparathyroidism
It occurs mainly in chronic kidney disease, where disturbances in phosphorus, vitamin D, and bone metabolism stimulate all parathyroid glands, which increase in size and PTH production.

It is characterized by:

  • Normal or low calcium
  • Very high PTH
  • Severe bone involvement
  • Vascular calcifications
  • Severe itching
  • Bone pain and fracture risk



C) Tertiary hyperparathyroidism
It occurs in patients with chronic kidney disease who receive a kidney transplant but whose parathyroid glands remain hyperactive despite improved kidney function.

In both conditions (secondary and tertiary), multigland disease is almost universal, so surgery is usually more extensive.

Preoperative localization methods (primary HPT)

To determine how many glands are affected and which ones, imaging studies are used. None is perfect: each provides different information.

Common studies:

  • Neck ultrasound
  • Sestamibi scan
  • 18F-fluorocholine PET
These methods help estimate how many glands are overactive and plan surgery accordingly.

Types of parathyroid surgery

The choice depends on the type of hyperparathyroidism, the concordance of imaging results, and the judgment of the specialized surgeon.

A) Surgery for primary hyperparathyroidism

1. Focused parathyroidectomy
(When imaging studies agree and a single adenoma is suspected). This is a targeted operation focused exclusively on the diseased gland.

Advantages:
  • Small incision
  • Less tissue manipulation
  • Shorter operative time
  • Faster recovery
  • Minimal risk of hypocalcemia

    • Important technical details:
    • Only the pathological gland is dissected
    • The remaining glands are preserved
    • Intraoperative PTH is frequently used to confirm cure


      • 2. Intraoperative PTH
      Intraoperative hormone measurement allows, with very high accuracy, confirmation that the diseased gland has been removed during surgery.

      It helps decide whether to:
      - wake the patient up, knowing the surgery was curative, or
      - continue exploring other glands until an adequate PTH drop is achieved.

      It is critical for:

      • Avoiding re-explorations
      • Confirming success in real time
      • Identifying hidden multigland disease


        • 3. Intraoperative biopsy
        In parathyroid surgery, immediate histologic confirmation can be very useful:

        • Verifies that the removed tissue is parathyroid
        • Distinguishes adenoma vs. hyperplasia
        • Helps decide whether to continue exploration


        4. Bilateral neck exploration
        Indicated when:

        • Imaging studies do not match
        • Multiglandular hyperplasia is suspected
        • There is a family history or MEN syndromes
        • Intraoperative PTH does not drop adequately
        • Prior re-operations
        It allows evaluation of all four glands and definitive treatment of the disease.


        B) Surgery for secondary / tertiary hyperparathyroidism

        In this setting, all glands are overactive, so surgery must be more extensive.

        1. Subtotal parathyroidectomy
        Three and a half glands are removed, leaving a very small remnant (50–80 mg) to avoid permanent hypocalcemia.


        2. Total parathyroidectomy with autotransplantation
        All four parathyroid glands are removed. A small fragment is implanted in the forearm or in the sternocleidomastoid muscle.

        Advantages of forearm implantation:
        • Easy monitoring
        • Easy re-intervention if recurrence occurs
        • Lower cervical risk

        3. Cryopreservation
        This involves storing frozen parathyroid tissue for potential future reimplantation if permanent hypoparathyroidism develops. Available at specialized centers.

        Technology and safety

        Safety in this surgery depends on the team’s experience and the use of different tools designed to reduce risks.

        Possible risks:

        • Temporary dysphonia: 1–5%
        • Permanent dysphonia: <0.5%
        • Transient hypocalcemia
        • Permanent hypocalcemia
        • Hematoma: 0.5–1%
        • Infection: <0.5%

        Available technologies:

        • Intraoperative monitoring of the laryngeal nerve: monitors voice function during surgery.
        • Continuous neurostimulation: alerts to traction or irritation of the nerve.
        • Magnification loupes: enable precise dissection.
        • ICG fluorescence: identifies parathyroids and assesses their blood supply.
        • Advanced hemostasis: safe sealing of vessels.
        • Specialized team: experienced anesthesia, instrumentation, and assistance.


        Recovery

        • Hospital stay: 12–24 hours
        • Usual activities: 3–7 days
        • Gradual return to physical activity: 2–4 weeks
        • Frequent calcium checks in the first days

        Many patients notice an improvement in overall well-being within 24–48 hours after surgery.

        Conclusion

        Parathyroid surgery is highly effective and, in experienced centers, offers cure rates above 95–99% for primary hyperparathyroidism, with excellent results in secondary and tertiary forms.

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