Pathology of parathyroid

Pathology of parathyroid 

Updated: 07/02/2023

© Jun Wang, MD, PhD

Anatomy/histology
  • Usually four glands between thyroid glands and trachea
  • Encapsulated glands with two types of cells
Chief cells: Small round nuclei, produce parathyroid hormone
Oxyphil cells: Eosinophilic granular cytoplasm, unknown function
  • May contain scattered adipocytes
Parathyroid hormone
  • Secreted in response to low blood calcium
  • Maintain calcium homeostasis with calcitonin, produced by C cell of thyroid
  • Binding to its receptor stimulates cAMP and phosphatidylinositol diphosphate
  • Five major functions:
Activates and increases the number of osteoclasts
Increases renal tubular reabsorption of calcium
Increases conversion of Vitamin D to active dihydroxy form in kidneys
Increases urinary phosphate excretion to reduce calcium loss
Increases GI calcium absorption
Diagnostic approaches
  • Laboratory studies: calcium, intact parathyroid hormone, parathyroid hormone related peptide (if high calcium, low PTH, likely tumor associated), renal function, etc
  • Image studies: 
    • Identify enlarged parathyroid gland/glands, sonography preferred
    • Sestamibi: Adenoma vs hyperplasia
    • CT, MRI, etc 
Work up for hypercalcemia

Hyperparathyroidism
Lack obvious signs and symptoms associated to excess calcium or parathyroid hormone
Usually incidental findings of elevated PTH with or without hypercalcemia
May progress to symptomatic hyperparathyroidism
Hypercalcemia without elevated PTH is most commonly caused by malignancy
Hypoparathyroidism
    Pseudohypoparathyroidism
    Neoplasm of parathyroid gland
    Practice questions



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