Primary Hyperparathyroidism

Primary Hyperparathyroidism

Primary Hyperparathyroidism

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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.

Parathyroid gland anatomy and histology

⭐ 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. Radiographic findings in primary hyperparathyroidism
    • 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:

ConditionSerum CaSerum PTHKey Feature
PHPT↑ / Inapp. N↑ Urine Ca, Cl/PO4 ratio > 33
FHH↑ (mild)N / Mild ↑ Urine Ca (Ca/CrCl ratio < 0.01)
Secondary HPT↓ / N↑↑Cause: CKD, Vit D def.
Tertiary HPT↑↑↑ (autonomous)Hx of prolonged Secondary HPT
  • USG neck (initial), Sestamibi scan (99mTc-MIBI)
  • SPECT/CT (Sestamibi + CT), 4D-CT, MRI (complex/recurrent)

Sestamibi scan showing parathyroid adenoma washout

⭐ 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.
      • Recurrent laryngeal nerve path near thyroid and parathyroid
    • 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.

Practice Questions: Primary Hyperparathyroidism

Test your understanding with these related questions

In hypoparathyroidism:

1 of 5

Flashcards: Primary Hyperparathyroidism

1/10

To prove the possibility of parathyroid graft hyperplasia, the ratio of the PTH levels should be greater than _____ on Casanova test

TAP TO REVEAL ANSWER

To prove the possibility of parathyroid graft hyperplasia, the ratio of the PTH levels should be greater than _____ on Casanova test

20:1

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