Parathyroid Flashcards
What action does Vitamin D have?
25-hydroxylase —kidney—> 1,25 (OH)2D
What is the calcium-sensing receptor?
GPCR that helps to regulate extracellular calcium homeostasis
when calcium is sensed there is negative feedback to reduce PTH level
What are the acute effects of hypercalcaemia?
- thirst
- dehydration
- confusion
- polyuria
(DI)
What are the chronic effects of hypercalcaemia?
- myopathy
- fractures
- depression
What are the causes of hypercalcaemia with a low PTH?
bone pathology
- with high ALP is mets or sarcoid
- with low ALP is myeloma
What are the causes of hypercalcaemia with high or normal PTH?
- high Urinary calcium is primary hyperparathyroidism
- low Urinary calcium is FHH
What are the most common causes of hypercalcaemia?
primary hyperparathyroidism
malignancy
What is the diagnosis of hypercalcaemia based on?
- raised serum calcium
- raised serum PTH (or inappropriately normal)
- high urine calcium excretion
What is the high ALP due to in malignancy?
- metastatic bone destruction
- PTHrp from solid tumours
- osteoclast activating factors
What is the acute treatment for hypercalcaemia?
- fluids
- ?loop diuretics (not thiazides)
- bisphosphonates to lower Ca
What are the treatment options for primary hyperparathyroidism?
- surgery: if v high Ca, below 50y, bad kidney function and end organ damage eg bone disease
- if no to surgery, give cincacalet
What must be done before surgery for primary hyperparathyroidism?
a sestamibi scan
What is primary hyperparathyroidism?
- primary overactivity of parathyroid gland ie adenoma
- high calcium and high PTH
What is secondary hyperparathyroidism?
- physiological response to low calcium and vit D
- low calcium and high PTH
What is tertiary hyperparathyroidism?
- parathyroid becomes autonomous after years of overactivity
- high calcium and high PTH
What is the parathyroid issue that patients with MEN1+2 always get?
parathyroid adenoma with hypercalcaemia at a young age
What is FHH?
Familial hypocalciuric hypercalcaemia needs higher levels of calcium to put PTH down resulting in high serum calcium and low urine calcium
What are the features of FHH?
- autosomal dominant
- familial
- benign
- genetic screening
What are the features of hypocalcaemia?
- long QT
- fitting
- paraesthesia of the toes and fingers
- muscle cramps
- muscle weakness
- bronchospasm
- Chovsteks sign which is twitching of the facial muscles when the facial nerve is tapped
What are the causes of hypoparathyroidism?
- DiGeorge
- Autoimmune
- Idiopathic
- Hypomagnesaemia
What can cause high intracellular calcium?
low magnesium as release of calcium is dependent on magnesium
What are the causes of hypomagnesemia?
- alcohol
- drugs
- GI illness
- pancreatitis
- malabsorption
What is pseudohypoparathyroidism?
due to PTH resistance so high PTH but low calcium and this is in short and fat patients
What does the sun do to form vit D?
sun acts on cholesterol which forms D3 which goes to the liver and then the kidney to become active
