Hyperparathyroidism Flashcards
What is hyperparathyroidism?
Excess secretion of PTH from the parathyroid glands; categorized as primary, secondary, or tertiary.
What are the functions of parathyroid hormone (PTH)?
- Regulate serum calcium
- Regulate serum phosphate
What cells in the parathyroid glands are responsible for the synthesis and secretion of PTH?
Chief cells
What triggers the secretion of PTH?
Changes in serum calcium levels via calcium-sensing receptor
What happens to PTH secretion during hypocalcaemia?
PTH secretion is increased
How does PTH increase serum calcium levels in the body?
- Promotes bone resorption, increasing calcium
- Stimulates calcium reabsorption in kidneys, inhibits phosphate reabsorption
- Indirectly increases absorption of calcium in small intestine by activating vitamin D
What is primary hyperparathyroidism?
Most common type; over secretion of PTH despite adequate calcium levels leading to hypercalcaemia.
What are the common causes of primary hyperparathyroidism?
- Adenoma (85%)
- Hyperplasia (14%)
- Carcinoma (<1%)
What are the blood results for primary hyperparathyroidism?
PTH and Ca2+
- Raised PTH
- Raised Ca2+
What is secondary hyperparathyroidism?
Disorder in calcium-phosphate-bone metabolism due to low serum calcium levels.
What are the common causes of secondary hyperparathyroidism?
- Chronic kidney disease
- Vitamin D deficiency
What are the blood results for secondary hyperparathyroidism?
PTH and Ca2+
- Raised PTH
- Low Ca2+
What is tertiary hyperparathyroidism?
Occurs following prolonged secondary hyperparathyroidism; glands secrete PTH autonomously leading to hypercalcaemia.
What are the blood results for tertiary hyperparathyroidism?
PTH and Ca2+
- Raised PTH
- Raised Ca2+
What are common symptoms of hypercalcaemia?
- Fatigue
- Polyuria and polydipsia
- Constipation
- Abdominal pain
- Vomiting
- Confusion
- Depression
- Bone pain
- Renal stones
What mnemonic is used to remember symptoms of hypercalcaemia?
Stones, bone, moans, groans
What are the differentials for hypercalcaemia?
- PTH-dependent (increased PTH): primary hyperparathyroidism, tertiary hyperparathyroidism
- PTH-independent (normal/decreased PTH): malignancy (breast, myeloma), medications (diuretics), granulomatous diseases (sarcoidosis, TB), other endocrine disorders (hypothyroid), rhabdomyolysis
What are the medical management options for hyperparathyroidism?
- Bisphosphonates
- Cinacalcet
What is the mechanism of action of cinacalcet?
Calcium-sensing receptor agonist that reduces PTH secretion and serum calcium
What is the surgical management for hyperparathyroidism?
Parathyroidectomy
