hyperparathyroidism
HYPERPARATHYROIDISM

Hyperparathyroidism is a condition wherein there is an excessive production of parathyroid hormone (PTH).

Primary hyperparathyroidism is the most common endocrine disorder and an important cause of hypercalcemia in ambulatory patients.

Classic signs and symptoms include bone disease, kidney stones and hypercalcinosis.

Primary goal of pharmacological therapy is to normalize calcium levels.

 

Surgical Intervention

Indications for Surgery

  • Symptomatic PHPT (nephrocalcinosis, osteitis fibrosa cystica, nephrolithiasis)
  • Threshold value of serum calcium >1 mg/dL (>0.25 mmol/L) above the upper normal limit
  • 24-hour urinary calcium >400 mg/dL
  • Peri- or post-menopausal women & men aged ≥50 years old who have bone density T-score of ≤-2.5 at the lumbar spine, femoral neck, total hip, or distal ⅓ radius
  • Premenopausal women & men <50 years old w/ bone density Z-score of ≤-2.5
  • Presence of vertebral fracture by x-ray or VFA w/ or without prior documentation
  • Creatinine clearance of <60 cc/min or when reduced by >30% in comparison w/ age-matched persons
  • Increased calcium-containing stone risk & marked hypercalciuria
  • Radiologic evidence of nephrocalcinosis or renal stones
  • Fragility fracture occurrence
  • Presence of neurocognitive &/or neuropsychiatric symptoms due to PHPT
  • Not desirable for medical surveillance
Absolute Contraindication
  • Lack of confirmation of diagnosis for persistent or recurrent PHPT
  • Inconclusive localization studies
  • Avoid blind explorations
Preoperative Management
  • 1000-1200 mg daily intake of Calcium is recommended for adults & PHPT patients
  • Preoperative vitamin D repletion is advised but must be done w/ caution in patients w/ hypercalciuria
  • Preoperative voice evaluation including specific injury involving subjective & significant voice changes or prior-at-risk surgery history
Surgical Techniques
Bilateral Neck Exploration
  • Standard surgical approach for most patients w/ PHPT
  • >95% long-term success rate w/ low rates of complications
  • Relies on visual & weight-based estimations of gland size to distinguish a single adenoma from multi-glandular disease
  • Preferred surgical technique in cases of discordant or non-localizing preoperative imaging
  • Suggested in cases of residual hyper-secreting tissue
Radio-guided Minimally Invasive Parathryroidectomy
  • Achieves 97-99% cure rate when done w/ intraoperative PTH measurement to confirm resection adequacy
  • Advantages:
    • Limits dissection
    • Faster recovery
    • Decreases postoperative discomfort
    • Less incision length
  • Preoperative imaging & other adjuncts are required prior to procedure
  • Indication:
    • Patient w/ high probability of solitary parathyroid adenoma w/ a significant uptake on sestamibi scintigraphy
    • Absence of thyroid nodules showing sestamibi uptake
    • Absence of familial hyperparathyroidism or MEN history
    • Absence of neck irradiation
    • Re-operation for persistent or recurrent hyperparathyroidism & ectopic adenoma
Gamma-probe Guided Surgery
  • More sensitive than gamma camera
  • For patients undergoing bilateral neck exploration w/ negative preoperative scintigraphy
  • 2 types:
    • Minimally invasive approach
    • Bilateral cervical exploration
  • Advantages: Easier surgical approach & shorter operation time
  • Verifies the correct excision of the pathological tissue & success of surgery
Concurrent Thyroidectomy
  • Performed in patients for thyroid disease requiring resection, sporadic parathyroid cancer suspect, abnormal intrathyroid parathyroid gland removal or access improvement
  • Indication: Concomitant thyroid disease during parathyroidectomy for PHPT w/ isolated thyroid disease
Immediate Postoperative Management
  • Monitor patient for complications (eg bleeding, hypocalcemia, vocal cord paralysis, laryngospasm)
  • Check:
    • Serum calcium concentration - reaches nadir within 24-36 hours post-surgery
    • Serum PTH level - within normal range within 30 hours post-surgery
  • Maintain low-calcium diet until normal serum calcium concentration is achieved
  • Seizure precaution should be observed at all times
  • “Hungry bone syndrome” - may develop in patients w/ large adenomas postoperatively
    • Associated w/ hypocalcemia, hypophosphatemia, & low urinary calcium excretion
  • Persistent hypercalcemia & elevated intact PTH levels post-surgery may indicated surgical failure
Surgical Adjuncts
Confirmation of Resected Parathyroid Tissue

  • Frozen section analysis
  • Ex vivo parathyroid aspiration

Gland Visualization
  • Intraoperative ultrasonography
  • Bilateral jugular venous sampling
  • Gamma-probe guidance
Intraoperative Rapid PTH Test
  • Performed in minutes to detect any remaining abnormal glands which provides real-time parathyroid function assessment
  • Terminate surgery if >50% fall in intraoperative PTH levels
  • Full neck exploration may be necessary if <50% fall in intraoperative PTH levels to look for other hyperactive glands & ectopic parathyroid glands (usually found in intrathyroid, retroesophageal, mediastinal)





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