Hyperparathyroidism

Question 1

What is hyperparathyroidism?

Answer 1

Excess secretion of PTH from the parathyroid glands; categorized as primary, secondary, or tertiary.

Question 2

What are the functions of parathyroid hormone (PTH)?

Answer 2

• Regulate serum calcium
• Regulate serum phosphate

Question 3

What cells in the parathyroid glands are responsible for the synthesis and secretion of PTH?

Answer 3

Chief cells

Question 4

What triggers the secretion of PTH?

Answer 4

Changes in serum calcium levels via calcium-sensing receptor

Question 5

What happens to PTH secretion during hypocalcaemia?

Answer 5

PTH secretion is increased

Question 6

How does PTH increase serum calcium levels in the body?

Answer 6

• 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

Question 7

What is primary hyperparathyroidism?

Answer 7

Most common type; over secretion of PTH despite adequate calcium levels leading to hypercalcaemia.

Question 8

What are the common causes of primary hyperparathyroidism?

Answer 8

• Adenoma (85%)
• Hyperplasia (14%)
• Carcinoma (<1%)

Question 9

What are the blood results for primary hyperparathyroidism?

PTH and Ca2+

Answer 9

• Raised PTH
• Raised Ca2+

Question 10

What is secondary hyperparathyroidism?

Answer 10

Disorder in calcium-phosphate-bone metabolism due to low serum calcium levels.

Question 11

What are the common causes of secondary hyperparathyroidism?

Answer 11

• Chronic kidney disease
• Vitamin D deficiency

Question 12

What are the blood results for secondary hyperparathyroidism?

PTH and Ca2+

Answer 12

• Raised PTH
• Low Ca2+

Question 13

What is tertiary hyperparathyroidism?

Answer 13

Occurs following prolonged secondary hyperparathyroidism; glands secrete PTH autonomously leading to hypercalcaemia.

Question 14

What are the blood results for tertiary hyperparathyroidism?

PTH and Ca2+

Answer 14

• Raised PTH
• Raised Ca2+

Question 15

What are common symptoms of hypercalcaemia?

Answer 15

• Fatigue
• Polyuria and polydipsia
• Constipation
• Abdominal pain
• Vomiting
• Confusion
• Depression
• Bone pain
• Renal stones

Question 16

What mnemonic is used to remember symptoms of hypercalcaemia?

Answer 16

Stones, bone, moans, groans

Question 17

What are the differentials for hypercalcaemia?

Answer 17

• 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

Question 18

What are the medical management options for hyperparathyroidism?

Answer 18

• Bisphosphonates
• Cinacalcet

Question 19

What is the mechanism of action of cinacalcet?

Answer 19

Calcium-sensing receptor agonist that reduces PTH secretion and serum calcium

Question 20

What is the surgical management for hyperparathyroidism?

Answer 20

Parathyroidectomy