Parathyroid functioning

Question 1

How many parathyroid glands are there and where are they located?

Answer 1

4 glands
Posterior aspect of thyroid

Question 2

What are the parathyroid glands very sensitive to?

Answer 2

Changes in calcium concentration

Question 3

The parathyroid releases ___ when there are low levels of calcium

Answer 3

PTH

Question 4

What cells in the parathyroid release PTH?

Answer 4

Chief cells

Question 5

The parathyroid releases _____ when there are high levels of calcium

Answer 5

Calcitonin

Question 6

What cells of the parathyroid releases calcitonin?

Answer 6

Parafollicular “c” cells of thyroid

Question 7

Does PTH or calcitonin seem to have a greater affect on calcium levels in the body?

Answer 7

PTH

Question 8

How does PTH affect bone formation and resorption?

Answer 8

PTH inhibits OPG (which competes with RANK-L) to allow RANK-L signalling from osteoblasts

Question 9

How does PTH increase calcium levels?

Answer 9

Increases calcium absorption in intestines

Increasing the reabsorption of calcium in the levels

Increasing osteoclast activity to release calcium from bones

Converts vitamin D to active forms to increase above

Question 10

How do we get enough vitamin D?

Answer 10

Sunlight
Food
Supplements

Question 11

What causes primary hyperparathryoidism?

Answer 11

Tumour of parathyroid gland releasing excessive PTH
Leads to hypercalcaemia

Question 12

How is primary hyperparathyroidism treated?

Answer 12

Surgical removal of tumour

Question 13

What are causes of secondary hyperparathyroidism?

Answer 13

Vitamin D deficiency
Chronic renal failure

Causes decreased absorption of calcium from intestines/kidneys/bones

Question 14

How does secondary hyperparathyroidism affect calcium levels?

Answer 14

Hypocalcaemia

Parathyroid tries to compensate by making lots of PTH

Question 15

What happens to the cells of the parathyroid gland in secondary hyperparathryoidism?

Answer 15

Hyperplasia occurs as making lots of PTH to compensate for low levels of calcium

Question 16

In secondary hyperparathyroidism, what will the levels of serum calcium and PTH be?

Answer 16

Low or normal serum Ca
High PTH

Question 17

How is secondary hyperparathyroidism treated?

Answer 17

Treat underlying cause:

Vitamin D supplements
Renal transplant

Question 18

What causes tertiary hyperparathyroidism?

Answer 18

Secondary hyperparathyroidism is treated reducing the need for lots of PTH but the glands still producing lots of PTH due to the hyperplasia.

Question 19

How is tertiary hyperparathyroidism treated?

Answer 19

Surgery to remove most tissue but leaving enough for normal amount of PTH to be secreted

Question 20

What are symptoms of hypercalcaemia?

Answer 20

Bones: excessive resorption, osteopenia)
Stones: calcium oxalate kidney stones
Moans: abdo pain and constipation
Psychedelic Groans: depression, anxiety

Question 21

What are ECG findings in hypercalcaemia?

Answer 21

Short QT

Question 22

How do you treat acute severe hypercalcaemia (complication of hyperparathyroidism)?

Answer 22

IV fluids
Bisphosphonates

Question 23

Is hyperparathyroidism or hypoparathyroidism more common?

Answer 23

Hyperparathyroidism