Parathyroid Pathologies Flashcards
1
Q
What causes parathyroid secretion?
A
- Parathyroid hormone is normally secreted in response to low ionised calcium levels by four parathyroid glands which are situated posterior to the thyroid gland
- The glands are controlled by positive feedback via Ca2+ levels
2
Q
What is the normal function of parathyroid hormone?
A
- They increase osteoclast activity releasing calcium and phosphate from bones
- Increased calcium and decreased phosphate reabsorption in the kidney
- Active calcitriol production is increased
- Overall effect is increased calcium and decreased phosphate
3
Q
What is hyperparathyroidism and what are the two types?
A
- Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood.
- This occurs either from a disorder within the parathyroid glands (primary hyperparathyroidism) or disorder outside the parathyroid glands (secondary hyperparathyroidism) resulting in them making too much PTH.
4
Q
What are the causes of primary hyperparathyroidism?
A
- Solitary adenoma
- Hyperplasia of all glands
- Parathyroid cancer
5
Q
How does primary hyperparathyroidism presented?
A
- Often asymptomatic
- Increased calcium on routine tests
- Weak
- Tired
- Depressed
- Thirsty
- Dehydrated but pilyuric
- Renal stones
- Abdominal pains
- Pancreatitis
- Ulcers
- Bone resorption effects of PTH can cause pain, fractures and osteopenia/osteoporosis
- Hypertension
6
Q
What the tests do you carry out to investigate primary hyperparathyroidism?
A
- Increased serum or urinary calcium and PTH (or if its inappropriately normal
- Decreased phosphate
- Raised ALP from bone activity
- 24hr urinary calcium
- Imaging to check for osteoporosis or osteopenia signs
- Decreased renal function
- Renal calculi
7
Q
How is primary hyperparathyroidism treated?
A
- Increase fluid intake to prevent renal stones
- AVoid thiazides and high calcium and vitamin D intake
- Excision of the adenoma or of all four hyperplastic glands to prevent fractures and peptic ulcers
- A calcimimetic (such as cinacalcet) is a potential therapy for some people with severe hypercalcemia and primary hyperparathyroidism who are unable to undergo parathyroidectomy and for secondary hyperparathyroidism on dialysis.
8
Q
How does cinacalet work?
A
- It is a calcimemetic so increases sensitivity of parathyroid cells to calcium therefore decreasing PTH secretion
9
Q
What are the side effects of cinacalcet?
A
- Myalgia
- Decreased testosterone
10
Q
What is secondary hyperparathyroidism?
A
- In people with secondary hyperparathyroidism, the high PTH levels are an appropriate response to low calcium
11
Q
What are the causes of secondary hyperparathyroidism?
A
- Vitamin D deficiency
- Chronic kidney disease
- Other causes of low blood calcium
12
Q
How is seconday hyperparathyroidism diagnosed?
A
- Low serumc calcium, high PTH
13
Q
How is secondary hyperparathyroidism treated?
A
- Treat underlying cause of this (usually vitamin D deficiency or chronic kidney failure).
- If this is successful PTH levels should naturally return to normal levels unless PTH secretion has become autonomous (tertiary hyperparathyroidism)
- Cinacalcet if PTH and parathyroidectomy is tricky
14
Q
What is tertiary hyperparathyroidism?
A
- Tertiary hyperparathyroidism is seen in patients with long-term secondary hyperparathyroidism, which eventually leads to hyperplasia of the parathyroid glands and a loss of response to serum calcium levels
- This disorder is most often seen in patients with end-stage kidney disease and is an autonomous activity.
- Serum calcium and parathyroid levels are raised
- Increased serum calcium from very increased secretion of PTH unlimited by feedback control
15
Q
What is malignant hyperparathyroidism?
A
- Parathyroid related protein is produced by some sqaumous cell lung cancers, breast and renal cell carcinomas
- This mimics PTH resulting in increased calcium
- PTH is decreased and calcium is raised
- PTHrP is not detected in the assay
27
Q
What are the causes of MEN 1, 2a and 2b syndrome?
A
