Hyperparathyroidism

Intro & Pathophysiology - PTH Power Play

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Clinical & Diagnosis - Spotting the PTH Villain

📌 Mnemonic: "Stones, Bones, Groans, Moans, Psychic Overtones"

• Clinical Features:

  • Renal: Stones (Ca oxalate/phosphate), nephrocalcinosis, polyuria, polydipsia.

  • Skeletal: Bone pain, fractures. Osteitis fibrosa cystica (OFC), brown tumors. Pathognomonic: subperiosteal resorption (radial aspect middle phalanges, distal clavicles, skull 'salt & pepper').

  • GI: Abdominal pain (groans), constipation, pancreatitis, PUD.

  • Neuro/Psych: Fatigue, depression, confusion, muscle weakness (moans).

• Investigations:
  • Labs: ↑Serum Ca (total & ionized), ↓Serum $PO_4$ (or normal/↑ in 2°/3° HPT), ↑PTH (key diagnostic), ↑ALP, ↑Urine Ca, ↑Urine cAMP. Vitamin D levels (for 2° HPT).
  • Imaging: X-rays (subperiosteal resorption, osteopenia, brown tumors, chondrocalcinosis), USG neck (adenoma), Sestamibi scan (localization of adenoma/hyperplasia), 4D CT.

  ⭐ Subperiosteal bone resorption, especially on the radial aspect of the middle phalanges, is pathognomonic for hyperparathyroidism.

Management & Complications - Taming the PTH Beast

• Primary HPT:
  • Surgical (Parathyroidectomy): Preferred for symptomatic; curative for adenoma.
    • Indications (Asymptomatic):
      • Serum Ca >1 mg/dL above ULN
      • T-score ≤ -2.5 (osteoporosis)
      • Age <50 yrs
      • CrCl <60 mL/min
      • 24hr urine Ca >400 mg/day
      • Nephrolithiasis/Nephrocalcinosis
  • Medical (Non-surgical): Cinacalcet (calcimimetic), Bisphosphonates (↑BMD), Vit D (if deficient), Hydration.
• Secondary HPT: Treat underlying cause (e.g., CKD, Vit D ↓). Phosphate binders, Vit D analogs (e.g., Calcitriol), Cinacalcet.
• Tertiary HPT: Parathyroidectomy usually required.

• Complications:
  • Bone: Pathological fractures (Osteitis Fibrosa Cystica), Brown tumors
  • Renal: Stones, Nephrocalcinosis, CKD progression
  • GI: Pancreatitis, PUD
  • Neuropsychiatric symptoms
  • Hypercalcemic Crisis (Emergency: IV fluids, Calcitonin, Bisphosphonates)
  • 📌 Post-Parathyroidectomy: Hungry Bone Syndrome (severe ↓Ca, ↓PO4, ↓Mg)

    ⭐ Hungry Bone Syndrome: Profound, prolonged hypocalcemia, hypophosphatemia, and hypomagnesemia post-parathyroidectomy due to rapid bone remineralization. Requires aggressive Ca/Mg replacement.

High‑Yield Points - ⚡ Biggest Takeaways

• Primary HPT: Usually parathyroid adenoma; causes hypercalcemia, hypophosphatemia, ↑PTH.
• Osteitis Fibrosa Cystica (OFC): Key bone manifestation with brown tumors, subperiosteal resorption.
• Radiological signs: "Salt-and-pepper" skull, bone cysts.
• Nephrolithiasis (calcium stones) is a common complication.
• Secondary HPT: Typically due to CKD; results in hypo/normocalcemia, hyperphosphatemia, ↑PTH.
• Tertiary HPT: Autonomous PTH secretion after chronic secondary HPT, leading to hypercalcemia.
• Sestamibi scan is crucial for localizing adenomas before surgery.