Hyperparathyroidism

Question 1

What is Hyperparathyroidism?

Answer 1

Hyperparathyroidism occurs when there is an excess of parathyroid hormone (PTH) being secreted from the parathyroid glands in the neck.

Question 2

Where is the parathyroid gland?

Answer 2

The parathyroid glands sit in the neck, on the posterior surface of the lateral lobes of the thyroid. Most adults have four, which are commonly described in two pairs (the superior and inferior parathyroid glands), although their positions in the neck can be highly variable.

Question 3

What is the role of parathyroid glands?

Answer 3

the role of the parathyroid glands is to regulate serum calcium and phosphate levels via the secretion of PTH.

Question 4

What is the chief cells of the parathyroid gland role?

Answer 4

The chief cells of the parathyroid glands are responsible for the synthesis and secretion of PTH, as well as the sensing of changes in serum calcium levels via the calcium-sensing receptor.

Question 5

What is the normal response to hypocalcaemia?

Answer 5

In response to hypocalcaemia, secretion of PTH is increased. PTH then raises serum calcium levels by acting on various organs throughout the body:

Question 6

Give the 3 ways in which parathyroid hormone acts to increase blood calcium:

Answer 6

1) increasing osteoclast activity in the bones to reabsorb calcium
2) increasing calcium reabsorption in the kidneys
3) increasing vitamin D activity so increased calcium is absorbed in the intestines

Question 7

What occurs in hyperthyroidism?

Answer 7

the homeostatic mechanism becomes decompensated, and the secretion of PTH is inappropriately high.

Question 8

What is primary hyperparathyroidism?

Answer 8

Primary hyperparathyroidism is the most common of the three types and is driven by a pathology of the glands. Here, one or more of the parathyroid glands is over-secreting PTH despite normal serum calcium, which over time leads to hypercalcaemia.

The aetiology can be adenoma (85%), hyperplasia (14%, may be associated with other conditions such as multiple endocrine neoplasias), or carcinoma (<1%).

Question 9

What is secondary hyperparathyroidism?

Answer 9

Secondary hyperparathyroidism is due to a disorder in calcium-phosphate-bone metabolism.

In response to low serum calcium levels as a result of another condition, commonly chronic kidney disease or vitamin D deficiency, the parathyroid glands secrete PTH. This may or may not normalise serum calcium levels, depending on the underlying condition.

Question 10

What are the two causes of secondary hyperparathyroidism?

Answer 10

1) insufficient vitamin D
2) chronic kidney disease

Question 11

What is tertiary hyperparathyroidism?

Answer 11

where secondary hyperparathyroidism continues for an extended period after the underlying cause has been treated, causing hyperplasia of the parathyroid glands, causing high PTH and hypercalcaemia

Question 12

What are some risk factors for hyperparathyroidism?

Answer 12

Most primary hyperparathyroidism is sporadic. Risk factors include being a post-menopausal woman, having previous radiation exposure to the neck, and taking lithium. The condition may also be associated with inherited disorders such as MEN.6

Secondary and tertiary hyperparathyroidism are associated with conditions affecting calcium metabolism (e.g. chronic kidney disease).

Question 13

Give 4 clinical presentations associated with hyperparathyroidism (stones, bones, groans and moans):

Answer 13

1) kidney stones
2) painful bones
3) abdominal groans (constipation, nausea and vomiting)
4) psychiatric moans (fatigue, depression and psychosis)

Question 14

What are typical symptoms of hypercalcaemia?

Answer 14

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

Question 15

Give 4 blood investigations used to investigate hyper/hypoparathyroidism

Answer 15

1) corrected calcium
2) serum PTH
3) vitamin D
4) U+Es (for CKD)

Question 16

What is corrected calcium?

Answer 16

albumin-adjusted serum calcium (as only 50% of Ca2+ is in its free ionised form while the rest is bound to albumin)

Question 17

What is a useful test to rule out malignancy?

Answer 17

Serum PTH

Question 18

Give 3 imaging methods used to investigate hyperparathyroidism:

Answer 18

1) DEXA scan (for reduced bone mineral density)
2) ultrasound of renal tract (renal stones)
3) ultrasound of neck (identifying adenomas of parathyroid glands)

Question 19

What is the treatment for primary hyperparathyroidism?

Answer 19

remove the tumour surgically

Question 20

What is the treatment for secondary hyperparathyroidism?

Answer 20

correcting the underlying vitamin D deficiency or chronic kidney disease

Question 21

What is the treatment for tertiary hyperparathyroidism?

Answer 21

surgically removing part of the parathyroid tissue

Question 22

Name the calcium-sensing receptor agonist which acts to reduce PTH secretion:

Answer 22

cinacalcet

Question 23

How does cinacalcet treat primary hyperparathyroidism in patients who cannot have surgery?

Answer 23

is is a calcium-sensing receptor agonist which reduces PTH secretion and therefor calcium

Question 24

When is cinacalcet indicated?

Answer 24

in primary hyperparathyroidism in patients who cannot have surgery

Question 25

What is the role of bisphosphates in hyperparathyroidism treatment?

Answer 25

they act to preserve bone density (does not affect serum calcium)

Question 26

True or false: PTH simultaneously stimulates phosphate release from bones

Answer 26

True

Question 27

What are 6 complications of primary hyperparathyroidism?

Answer 27

1. Osteoporosis
2. Renal impairment
3. Calculi
4. Pseudogout
5. Pancreatitis
6. Cardiovascular disease