C - Clinical Chemistry CPC Flashcards
what electrolyte imbalance causes depression
low CA
what key symptom does high ca cause
paralysis
what does hyperventilation do to ca level
low
what key symptom can high or low K give
arrhythmias
what type of fracture is seen in hyperCA
smith’s
Ix for renal stones
abdo XR
abdo USS
ca plasma
what type of stone is seen on abdo XR & what can it be confused with
calcified stones only
gall stones
commonest cause of hyperCA in hospital
cancer
commonest cause of hyperCa in community
primary hyperparathyroidism
rare cause of hyperCA
sarcoidosis
ix to distinguish between the 3 causes of hyperCa
PTH
describe PTH levels in primary hyperparathyroidism vs cancer
hyperPTH = high/inappropriately NORMAL
cancer = low / 0
what is the commonest cause of primary hyperPTH
PT adenoma 85%
3 actions of PT adenoma & overall effect
increases bone resorption
activates Vit D
retains Ca in urine
—> increases Ca
what other enzyme is also high in primary hyperPTH & why
ALP - increased bone turnover
sx of primary hyperPTH
stones - kidney
bones - fracture, pain
moans - depression
groans - abdo pain, polydypsia and polyuria
what condition does primary hyperPTH cause and why
nephrogenic DI
- ca excreted in urine, which is osmotic so draws out water
name a sign of chronic high ca
band keratopathy - ca band in eye
list complications of primary hyperPTH
renal stones
pancreatitis
peptic ulcer
changed skeleton
osteitis fibrosa et cystica
list RFs for developing renal stones
FH
dehydration
hypercalinuria
high ca
hyperPTH
urgent mx of high ca & indications
IV fluids - max 4L/day unless HF
bisphosphonates if fluids don’t work
2 drawbacks of giving bisphosphonates in primary hyperPTH
get low ca once PTH gland removed
take 4 days to work
3 non urgent Mx steps of primary hyperPTH
keep drinking fluids
avoid thiazides
Parathyroidectomy
prognosis of primary hyperPTH
excellent
what would a PTH adenoma histology show
CAPSULATED - shows its benign
what would an x ray of high ca show
radial aspect cystic change
looser zones
what would bone histology of high ca show
brown tumours - made of multinucleated giant cells (hyperplastic osteoclasts)
dyspnoea in an afro caribean with high Ca. Dx?
sarcoidosis
2 Ix for sarcoid and their results
chest XR - bilateral hilar lymphadenopathy
biopsy - multinuclear giant cells, smooth non caseating granulomas
PTH and Ca in sarcoidosis
high Ca
low PTH
pathophysiology of sarcoidosis
macrophages express 1 alpha hydroxylase to activate vit D, so get a massive activation of vit D and high ca
describe annual changes of sarcoid pattern
seasonal - more Ca / Sx in summer as more sunlight to create vit D
Tx of sarcoid
prednisolone
what peptide is found on cancer cells causing bone problems
PTH related peptide (PTHRP)
how does PTHRP allow bone destruction in cancer
expressed on some cancer cells, so cells allow bone invasion as cancer recognised as PTH
when is PTHRP physiological
in utero - allows baby to steal mum’s Ca from her bones
Mx of bony mets
bisphosphonates - alleviates pain