What are the criteria for parathyroidectomy in primary hyperparathyroidism?

Criteria for Parathyroidectomy in Primary Hyperparathyroidism

Parathyroidectomy should be recommended for patients with primary hyperparathyroidism who have persistent serum levels of intact PTH >800 pg/mL (88.0 pmol/L), associated with hypercalcemia and/or hyperphosphatemia that are refractory to medical therapy. 1

Indications for Parathyroidectomy

• Parathyroidectomy is indicated for all symptomatic patients with primary hyperparathyroidism 2
• Surgery should be considered for most asymptomatic patients as it is more cost-effective than observation or pharmacologic therapy 2
• Specific criteria for surgery in asymptomatic patients include:
  • Age younger than 50 years 3
  • Significant hypercalcemia 3
  • Impaired renal function (GFR < 60 mL/min/1.73 m²) 1
  • Presence of kidney stones or nephrolithiasis 3, 4
  • Osteoporosis or evidence of bone demineralization 3
  • Presence of calciphylaxis with elevated PTH levels (around 500 pg/mL) 1

Pre-surgical Evaluation

• Imaging of parathyroid glands is recommended prior to surgery, particularly for re-exploration parathyroid surgery 1
• Recommended imaging modalities include:
  • 99 Tc-Sestamibi scan (highest sensitivity) 1
  • Ultrasound 1
  • CT scan 1
  • MRI 1
• Preoperative parathyroid biopsy should be avoided 2
• Vitamin D status should be assessed (25-hydroxyvitamin D measurement) and deficiency should be corrected prior to surgery 2

Surgical Approaches

• Both focused, image-guided surgery (minimally invasive parathyroidectomy) and bilateral exploration are appropriate operations with high cure rates 2
• Effective surgical therapy can be accomplished by:
  • Subtotal parathyroidectomy 1
  • Total parathyroidectomy with parathyroid tissue autotransplantation 1
• Total parathyroidectomy is not recommended for patients who may subsequently receive a kidney transplant due to potential difficulties in controlling serum calcium levels post-transplantation 1
• For minimally invasive parathyroidectomy, intraoperative parathyroid hormone monitoring via a reliable protocol is recommended 2

Post-surgical Management

• Blood level of ionized calcium should be measured every 4-6 hours for the first 48-72 hours after surgery, then twice daily until stable 1
• If blood levels of ionized calcium fall below normal (<0.9 mmol/L), calcium gluconate infusion should be initiated at 1-2 mg elemental calcium per kilogram body weight per hour 1
• When oral intake is possible, patients should receive:
  • Calcium carbonate 1-2 g three times daily 1
  • Calcitriol up to 2 μg/day 1
• If the patient was receiving phosphate binders prior to surgery, this therapy may need to be discontinued or reduced based on serum phosphorus levels 1

Benefits of Parathyroidectomy vs. Medical Management

• Parathyroidectomy results in greater normalization of serum calcium and PTH levels compared to calcimimetics 5
• Surgery significantly improves bone mineral density (BMD), particularly cortical BMD, compared to medical therapy 5
• Parathyroidectomy significantly decreases stone recurrence in patients with nephrolithiasis 4
• Normalization of PTH through surgery is associated with significant improvement in spine and femur BMD 5

Common Pitfalls and Caveats

• Not all patients with calciphylaxis have high levels of PTH, and parathyroidectomy should not be undertaken in the absence of documented hyperparathyroidism 1
• Despite parathyroidectomy, persistent hypercalciuria may be detected in approximately 47% of patients, requiring continued monitoring 4
• The possibility of multigland disease should be routinely considered, and minimally invasive parathyroidectomy is not routinely recommended for known or suspected multigland disease 2
• Surgeons who perform a high volume of parathyroidectomies have better outcomes 2

By following these criteria and recommendations, clinicians can appropriately select patients for parathyroidectomy and optimize outcomes in the management of primary hyperparathyroidism.