Hyperparathyroidism and hypercalcaemia Flashcards
causes of primary hyperpara
adenoma (80%)
hyperplasia (20%)
causes of secondary hyperpara
CKD!!
vit d deficiency
why does CKD cause hyperparathyroidism
Failing kidneys don’t convert enough vitamin D to its active form, and also don’t adequately excrete phosphate. The high phosphate causes insoluble calcium phosphate to form which resultantly removes calcium from the circulation.
Reduced active vit d causes less ca to be absorbed from intestine and less to be removed from bone.
Both processes lead to hypocalcemia and hence secondary hyperparathyroidism.
another mechanism by which PTH may be increased
PTH secreting cancer - often squamous cell lung ca
symptoms (of hypercalcaemia really)
bones, stones, moans (con2fused!), groans (vomiting and constipation)
polyuria, polydypsia
anorexia, weight loss
calcaemia, phosphataemia and PTH in a) primary and b) secondary
a) hypercal, hypophos (decreased resorption in kidneys), hyper PTH
b) hypocal, hyperphos (kidney disease), hyper PTH
effects of PTH
secreted in response to hypocal.
BONE - stimulates osteoclasts to release Ca into blood
KIDNEY - increase calcium reabsorp, increased phosphate excretion, stimulates activation of vit D
(the vit D then causes increased Ca uptake in intestine)
how is vit d involved
mediates absorption of ca and phosphate from intesti
difference between primary and secondary hyperparathyroidism
primary: PTH raised because of oversecretion
secondary: excess PTH secreted in response to low calcium
emergency rx of hypercalcaemia?
fluids (sodium is excreted and pulls Ca with it). 4-6L in 24h IV bisphosphonates (pomidronate). not straight away, only if not coming down with fluid
rx primary hyperparathyroid
increase fluid intake to prevent stones
avoid thiazides
avoid high ca and vit d intake
excision of adenoma if hypercalcaemia, osteoporosis, rental stones, reduced renal function
treatment of secondary hyperparathyroid
treat the hypocal and it will sort itself out:
give vit d (calcitriol)
in CKD: phosphate binders to reduce phosphate
what value should you admit if hypercalcaemia
greater than 3
greater than 3.5 -> you’re worried!!!
what investigation is vital in hypercal
ECG! (can have prolonged QT)
2 most common causes of hypercal
malignancy
primary hyperparathyroid
