PTH Flashcards
What causes PTH release
Low ionised calcium levels
From four parathyroid glands posterior to thyroid
How does PTH act?
Increased osteoclast activity released Ca and PO4 from the bones
Increased calcium and reduced phosphate reabsorption in the kidney
Increased production of active 1,25-dihydroxyvitamin D
This enhances absorption of calcium in the intestine
The overall effect is increase in calcium and reduction in phosphate
What are causes of primary hyperparathyroidism?
Solitary adenoma
Hyperplasia of all galnds
Parathyroid cancer
What is the presentation of hyperparathyroidism?
Raised calcium on routine tests
1 Raised calcium: weak, tired, depressed, thirsty, dehydrated-but-polyuric, renal stones, abdominal pain, pancreatitis, ulcers (mostly duodenal)
2 Bone resorption effects of PTH can cause pain, fractures, osteopenia/osteoporosis
3 HYpertension
What tests for hyperparathyroidism?
Calcium raised
PTH raised
Low phosphate unless in renal failure
Raised ALP from bone activity
DEXA scan for osteoporosis
What treatment for hyperparathyroidism?
If mild: increase fluid intake to prevent stones, high calcium and vitamin D intake
Excision of adenoma or of all four hyper plastic glands prevents fractures and peptic ulcers.
Indication:
High serum or urinary calcium, bone disease, osteoporosis, renal calculi, renal function reduced, under 50 years age
What are the tests in secondary hyperparathyroidism? causes?
Low Calcium, raised PTH (appropriately)
Causes: reduced vitamin D intake, chronic renal failure
What are the tests in tertiary hyperparathyroidism? When does this occur?
Raised Calcium, very high PTH (inappropriately)
Occurs after prolonged secondary hyperparathyroidism, causing glands to acut autonomously having undergone hyperplastix or adenomatous change. This causes increase calcium from increase secretion of PTH unlimited by feedback control.
What is malignant hyperparathyroidism?
Parathyroid related protein (PTHrP) is produced by some squamous cell lung cancers, breast, and renal cell carcinomas.
This mimics PTH resulting in increased calcium.
What is primary hypoparathyroidism? What do tests show? What are signs? Treatment?
PTH secretion falls duets gland failure
Low calcium raised phosphate
Sign soft hypocalcaemia: SPASMODIC Spasms Perioral paraethesiae Anxious, irritable Seizures Muscle tone increased Orientation impaired and confusion Dermatitis Impetigo herpetiforms (low calcium and pustules in pregnancy Chovstek's sign - corner of mouth twitches when facial nerve is trapped over parotid
Treat: calcium supplements, calcitriol
