C - Clinical Chemistry CPC

Question 1

what electrolyte imbalance causes depression

Answer 1

low CA

Question 2

what key symptom does high ca cause

Answer 2

paralysis

Question 3

what does hyperventilation do to ca level

Answer 3

low

Question 4

what key symptom can high or low K give

Answer 4

arrhythmias

Question 5

what type of fracture is seen in hyperCA

Answer 5

smith’s

Question 6

Ix for renal stones

Answer 6

abdo XR
abdo USS
ca plasma

Question 7

what type of stone is seen on abdo XR & what can it be confused with

Answer 7

calcified stones only
gall stones

Question 8

commonest cause of hyperCA in hospital

Answer 8

cancer

Question 9

commonest cause of hyperCa in community

Answer 9

primary hyperparathyroidism

Question 10

rare cause of hyperCA

Answer 10

sarcoidosis

Question 11

ix to distinguish between the 3 causes of hyperCa

Answer 11

PTH

Question 12

describe PTH levels in primary hyperparathyroidism vs cancer

Answer 12

hyperPTH = high/inappropriately NORMAL
cancer = low / 0

Question 13

what is the commonest cause of primary hyperPTH

Answer 13

PT adenoma 85%

Question 14

3 actions of PT adenoma & overall effect

Answer 14

increases bone resorption
activates Vit D
retains Ca in urine
—> increases Ca

Question 15

what other enzyme is also high in primary hyperPTH & why

Answer 15

ALP - increased bone turnover

Question 16

sx of primary hyperPTH

Answer 16

stones - kidney
bones - fracture, pain
moans - depression
groans - abdo pain, polydypsia and polyuria

Question 17

what condition does primary hyperPTH cause and why

Answer 17

nephrogenic DI
- ca excreted in urine, which is osmotic so draws out water

Question 18

name a sign of chronic high ca

Answer 18

band keratopathy - ca band in eye

Question 19

list complications of primary hyperPTH

Answer 19

renal stones
pancreatitis
peptic ulcer
changed skeleton
osteitis fibrosa et cystica

Question 20

list RFs for developing renal stones

Answer 20

FH
dehydration
hypercalinuria
high ca
hyperPTH

Question 21

urgent mx of high ca & indications

Answer 21

IV fluids - max 4L/day unless HF
bisphosphonates if fluids don’t work

Question 22

2 drawbacks of giving bisphosphonates in primary hyperPTH

Answer 22

get low ca once PTH gland removed
take 4 days to work

Question 23

3 non urgent Mx steps of primary hyperPTH

Answer 23

keep drinking fluids
avoid thiazides
Parathyroidectomy

Question 24

prognosis of primary hyperPTH

Answer 24

excellent

Question 25

what would a PTH adenoma histology show

Answer 25

CAPSULATED - shows its benign

Question 26

what would an x ray of high ca show

Answer 26

radial aspect cystic change
looser zones

Question 27

what would bone histology of high ca show

Answer 27

brown tumours - made of multinucleated giant cells (hyperplastic osteoclasts)

Question 28

dyspnoea in an afro caribean with high Ca. Dx?

Answer 28

sarcoidosis

Question 29

2 Ix for sarcoid and their results

Answer 29

chest XR - bilateral hilar lymphadenopathy
biopsy - multinuclear giant cells, smooth non caseating granulomas

Question 30

PTH and Ca in sarcoidosis

Answer 30

high Ca
low PTH

Question 31

pathophysiology of sarcoidosis

Answer 31

macrophages express 1 alpha hydroxylase to activate vit D, so get a massive activation of vit D and high ca

Question 32

describe annual changes of sarcoid pattern

Answer 32

seasonal - more Ca / Sx in summer as more sunlight to create vit D

Question 33

Tx of sarcoid

Answer 33

prednisolone

Question 34

what peptide is found on cancer cells causing bone problems

Answer 34

PTH related peptide (PTHRP)

Question 35

how does PTHRP allow bone destruction in cancer

Answer 35

expressed on some cancer cells, so cells allow bone invasion as cancer recognised as PTH

Question 36

when is PTHRP physiological

Answer 36

in utero - allows baby to steal mum’s Ca from her bones

Question 37

Mx of bony mets

Answer 37

bisphosphonates - alleviates pain