Parathyroid Glands: General Considerations

Hyperparathyroidism

Definition: Hyperparathyroidism is the state of elevated serum parathyroid hormone (PTH) as a result of excessive secretion (overproduction).

• Hyperparathyroidism is the most common pathologic condition affecting the parathyroid glands.

• Causes of hyperparathyroidism due to parathyroid-related disorders are listed in Box 31-1 .

  Box 31-1

  Causes of Hyperparathyroidism Due to Parathyroid-Related Disorders

  Primary

  • Parathyroid proliferative disease, including:

    • –

      Adenoma (approximately 85% of cases)

    • –

      Hyperplasia (approximately 13% of cases)

    • –

      Carcinoma (approximately 2% of cases)

  • Syndromes associated with hyperparathyroidism include (see Section 10 for more complete discussion):

    • –

      Multiple endocrine neoplasia (MEN)-1

    • –

      MEN-2A

    • –

      Hyperparathyroidism-Jaw syndrome

    • –

      Less common syndromes associated with hyperparathyroidism include:

      • –

        Familial hypocalciuric hypercalcemia

      • –

        Familial hypercalcemic hypercalciuria

      • –

        Neonatal severe primary hyperparathyroidism

      • –

        Familial isolated hyperparathyroidism

  • Rarely may be associated with parathyroid cyst

  Secondary

  • Chronic renal failure (most common)

  • Dietary vitamin D deficiency or abnormalities of vitamin D metabolism

  • Malabsorption

  • Pseudohypoparathyroidism

  Tertiary

  • Same as secondary hyperparathyroidism

• Parathyroid-independent hypercalcemic disorders are listed in Box 31-2 .

  Box 31-2

  Parathyroid-Independent Hypercalcemia

  • Hypercalcemia of malignancy

  • Vitamin D intoxication

  • Granulomatous diseases

    • –

      Sarcoidosis

    • –

      Other

  • Hyperthyroidism

  • Vitamin A intoxication

  • Adrenal insufficiency

  • Thiazide diuretics

  • Milk-alkali syndrome

  • Renal failure

  • Immobilization

  • Other

• Hyperparathyroidism is divided into primary, secondary, and tertiary categories.

• Reference range for intact PTH in normal adults is 10-65 pg/ml.