Primary Hyperparathyroidism

PHPT Basics - Gland Overdrive

Primary Hyperparathyroidism (PHPT): Autonomous ↑PTH secretion causing hypercalcemia. Common in postmenopausal women.

• Etiology: Most commonly:
  • Solitary Adenoma (80-85%)
  • Glandular Hyperplasia (10-15%)
  • Parathyroid Carcinoma (<1%)
• Associations: MEN 1 (📌 3Ps: Parathyroid, Pituitary, Pancreas), MEN 2A.
• PTH Action: ↑Bone resorption (↑Ca²⁺, ↑PO₄³⁻). Kidney: ↑Ca²⁺ reabsorption, ↓PO₄³⁻ reabsorption, ↑Vit D activation. Intestine (via Vit D): ↑Ca²⁺ absorption.

⭐ Most common cause of PHPT is a single parathyroid adenoma (80-85%).

Clinical Picture - Symptom Symphony

• Many patients are asymptomatic (discovered on routine labs).
• Symptomatic presentation: 📌 "Bones, stones, abdominal groans, and psychic moans."
  • Skeletal: Osteitis fibrosa cystica (brown tumors), bone pain, fractures, subperiosteal resorption.
  • Renal: Nephrolithiasis (calcium oxalate), nephrocalcinosis, polyuria.
  • GI: Constipation, peptic ulcer disease (PUD), pancreatitis, nausea.
  • Neuromuscular/Psychiatric: Fatigue, weakness, depression, confusion, memory loss.
  • Cardiovascular: Hypertension (HTN), arrhythmias, short QT interval.

⭐ Nephrolithiasis (calcium oxalate stones) is the most common symptomatic manifestation of PHPT (Primary Hyperparathyroidism).

Diagnostic Drilldown - Lab & Localize

Biochemical Profile (PHPT):

• ↑ Serum Ca (total & ionized), ↑ PTH (inappropriately normal/high)
• ↓ Serum PO4, ↑ ALP
• Assess Vitamin D (replete if deficient)

Key Differentiators:

• USG neck (initial), Sestamibi scan (99mTc-MIBI)
• SPECT/CT (Sestamibi + CT), 4D-CT, MRI (complex/recurrent)

⭐ A Sestamibi scan combined with SPECT/CT is highly effective for pre-operative localization of solitary parathyroid adenomas.

Treatment Tactics - Surgical Solutions

• Surgical Indications (NIH 2022):
  • Age <50
  • Serum Ca >1 mg/dL above ULN
  • CrCl <60 mL/min
  • T-score ≤ -2.5 SD or vertebral fracture
  • Nephrolithiasis/calcinosis
• Medical Management (Non-surgical):
  • Cinacalcet, bisphosphonates
  • Fluids, Vit D repletion (if deficient)
• Surgical Options:
  • Minimally Invasive Parathyroidectomy (MIP) / Focused (if localized)
  • Bilateral Neck Exploration (BNE)
• Intraoperative PTH (IOPTH):
  • Miami criterion: >50% ↓ from baseline AND into normal range in 10-15 min post-excision.

⭐ Successful parathyroidectomy is confirmed by intraoperative PTH (IOPTH) monitoring, with a >50% drop from pre-excision baseline (Miami criterion) indicating cure.

Aftermath & Alerts - Post-Op Pointers

• Post-Op Complications:
  • Hypocalcemia:
    • Transient (common) vs. Permanent hypoparathyroidism.
    • Hungry Bone Syndrome (HBS): severe ↓$Ca^{2+}$, ↓$PO_4^{3-}$, ↓$Mg^{2+}$.
  • Recurrent Laryngeal Nerve (RLN) injury: hoarseness.
    • 
  • Neck Hematoma (⚠️ airway risk!), Infection.
• Hypocalcemia Management:
  • Oral/IV Calcium, Vitamin D (Calcitriol).
• Follow-up: Serial serum $Ca^{2+}$ monitoring.

⭐ Hungry Bone Syndrome, characterized by severe and prolonged hypocalcemia, hypophosphatemia, and hypomagnesemia, can occur post-parathyroidectomy in patients with pre-existing severe bone disease.

High‑Yield Points - ⚡ Biggest Takeaways

• Solitary parathyroid adenoma is the most common cause (~85%).
• Hallmark: Hypercalcemia (↑Ca²⁺) with inappropriately elevated PTH.
• Symptoms: "Stones, bones, groans, moans"; nephrolithiasis is most common. Many are asymptomatic.
• Bone disease: Osteitis fibrosa cystica (brown tumors) is classic but rare.
• Localization: Sestamibi scan and neck ultrasound are key pre-op.
• Treatment: Surgical parathyroidectomy is curative for symptomatic patients.
• Intraoperative PTH monitoring (drop >50%) confirms successful resection.