Hyperparathyroidism (B)

Question 1

Where are parathyroid glands?

Answer 1

there are four parathyroid glands situated in four corners of the thyroid gland.

Question 2

What is the role of parathyroid glands?

Answer 2

The parathyroid glands, specifically the chief cells in the glands, produce parathyroid hormone in response to hypocalcaemia (low blood calcium).

Question 3

How does parathyroid hormone increase calcium?

Answer 3

Increasing osteoclast activity in bones (reabsorbing calcium from bones)
Increasing calcium absorption from the gut
Increasing calcium absorption from the kidneys
Increasing vitamin D activity

Question 4

What is the role of Vitamin D?

Answer 4

Vitamin D acts to increase calcium absorption from the intestines. Parathyroid hormone acts on vitamin D to convert it into active forms. So vitamin D and parathyroid hormone act together to raise blood calcium levels.

Question 5

What is primary hyperparathyroidism and how is it treated?

Answer 5

Primary hyperparathyroidism is caused by uncontrolled parathyroid hormone produced directly by a tumour of the parathyroid glands. This leads hypercalcaemia: an abnormally high level of calcium in the blood. This is treated by surgically removing the tumour.

Question 6

What is secondary hyperparathyroidism and how is it treated?

Answer 6

This is where insufficient vitamin D or chronic renal failure leads to low absorption of calcium from the intestines, kidneys and bones. This causes hypocalcaemia: a low level of calcium in the blood.

The parathyroid glands reacts to the low serum calcium by excreting more parathyroid hormone. Over time the total number of cells in the parathyroid glands increase as they respond to the increased need to produce parathyroid hormone. This is called hyperplasia. The glands become more bulky. The serum calcium level will be low or normal but the parathyroid hormone will be high. This is treated by correcting the vitamin D deficiency or performing a renal transplant to treat renal failure.

Question 7

What is tertiary hyperparathyroidism?

Answer 7

This happen when secondary hyperparathyroidism continues for a long period of time. It leads to hyperplasia of the glands. The baseline level of parathyroid hormone increases dramatically. Then when the cause of the secondary hyperparathyroidism is treated the parathyroid hormone level remains inappropriately high. This high level of parathyroid hormone in the absence of the previous pathology leads to high absorption of calcium in the intestines, kidneys and bones and causes hypercalcaemia. This is treated by surgically removing part of the parathyroid tissue to return the parathyroid hormone to an appropriate level.

Question 8

Summarise Hyperparathyroidism

Answer 8

Hyperparathyroidism

           Cause    PTH    Calcium

Primary Tumour H H

Secondary

Question 9

Treating hyperparathyroidism

Answer 9

For acute hypercalcemia, give
IV fluids (with a loop diuretic in the setting of renal or heart failure), IV bisphosphonate,
and
calcitonin.
■ Oral phosphate binders (aluminum hydroxide, calcium salts, sevelamer hydrochloride, and lanthanum carbonate) and dietary phosphate restriction are used in patients with 2° hyperparathyroidism regardless of dialysisstatus.
■ Cinacalcet ↓ PTH as well as calcium and phosphate and may be a helpful adjunct in end-stage renal disease