Endocrinology - Hyperparathyroidism Flashcards
What is the normal function of the parathyroid gland?
Releases PTH in response to low serum calcium
PTH raises serum calcium by:
- Increasing the absorption of calcium from the small intestine
- Increasing the re-absorption from kidneys (reducing excretion)
- Increasing osteoclast activity
What is the function of PTH?
PTH raises serum calcium by:
- Increasing the absorption of calcium from the small intestine
- Increasing the re-absorption from kidneys (reducing excretion)
- Increasing osteoclast activity
It also acts on vitamin D to convert it to active forms- which helps to increase absorption of calcium into serum
What can deficiency in Vitamin D cause?
Hypocalcaemia
What is primary hyperparathyroidism?
Uncontrolled PTH being produced by tumour of parathyroid gland
What is the treatment of primary hyperthyroidism?
Removal of the tumour causing excess PTH release
What is secondary hyperparathyroidism?
Caused by either deficiency in vitamin D or chronic renal failure leads to:
- Reduced calcium absorption from SI
- Reduced calcium re-absorption from kidneys
- Reduced absorption of calcium from bones
Leads to low calcium levels and PT glands excrete more PTH
Over time the PT gland undergoes hyperplasia due to increased need for PTH to stimulate calcium release
Treatment of secondary hyperparathyroidism?
Treat underlying cause:
- Vitamin D supplementation
- Renal transplant in renal failure
What is tertiary hyperparathyroidism?
Caused by long-term secondary hyperparathyroidism causing hyperplasia of the gland
The baseline amount of PTH released increases
Then when the cause of the secondary hyperparathyroidism is treated the parathyroid hormone level remains inappropriately high
Causes hypercalcaemia in the blood
Treatment of tertiary hyperparathyroidism?
Surgically removing part of the parathyroid tissue to return the parathyroid hormone to an appropriate level.
High PTH
Low calcium
Primary hyperparathyroidism
Uncontrolled PTH release from PT gland caused by tumour
High PTH
Low or normal calcium
Secondary hyperparathyroidism
Caused by low vitamin D and CKD
High PTH
High Calcium
Tertiary hyperparathyroidism
Cause is hyperplasia due to long term secondary hyperparathyroidism
