electrolyte abnormalities

Question 1

causes of hypercalcaemia, main 2 ?

Answer 1

2 conditions account for 90%;
- primary hyperparathyroidism
- malignancy

others
- sarcoidosis (/other causes of granulomas)
- vit D intoxication
- acromegaly
- thyrotoxicosis
- thiazides
- dehydration

Question 2

endocrine conditions that can cause hypercalcaemia

Answer 2

addisons
acromegaly
thyrotoxicosis
pagets disease of the bone

Question 3

key hormone level to check in hypercalcaemia

Answer 3

parathyroid hormone

Question 4

features of hypercalcaemia

Answer 4

bones, stones, groans, psychic moans

• corneal calcification
• hypertension

Question 5

changes in ECG with hypercalcaemia

Answer 5

**shortened QT interval **

Question 6

causes of hypocalcaemia

Answer 6

chronic kidney disease
hypOparathyroidism
rhabdomyolysis

acute pancreatitis

Question 7

ECG changes in hypOcalcaemia

Answer 7

prolonged QT !!

Question 8

management of hypocalcaemia

Answer 8

if severe = IV calcium replacement
–> IV calcium gluconate 10ml 10% over 10mins

ECG monitor

(severe = muscle spasms, seizures or prolonged QT)

Question 9

features of hypocalcaemia

Answer 9

tetany - muscle twitching, cramping, spasm
perioral paraesthesia
chronic - depression, cataracts

Trousseau’s sign
Chvostek’s sign

Question 10

Trousseau’s sign + Chvostek’s sign

Answer 10

indicate hypocalcaemia !

Trousseau’s - carpal spasm if brachial artery occluded by inflating BP cuff

Chvostek’s - tapping over parotid causes facial muscles to twitch

Question 11

ECG changes in hyperkalaemia

Answer 11

tall tented T waves
small P waves
widened QRS

sinusoidal wave pattern

Question 12

causes of hyperkalaemia

Answer 12

AKI
drugs
metabolic acidosis
addisons
rhabdomyolysis
massive blood transfusion

Question 13

drugs that cause hyperkalaemia

Answer 13

• ACEi
• ARBs
• spirnolactone
• ciclosporin
• heparin
• potassium sparing diruetics

Question 14

stages of hyperkalaemia

Answer 14

mild - 5.5-5.9
mod - 6-6.4
severe - >=6.5

Question 15

mangement of severe hyperkalaemia

Answer 15

IV calcium gluconate
insulin/dextrose infusion
- nebulised salbutamol may be given to temporarily lower the serum postassium

then
- stop exacerbating drugs - ACEi
- treat underlying cause
- lower total body potassium - calcium resonium, loop diuretics, dialysis

Question 16

calcium gluconate in the mx of hyperkalaemia

Answer 16

stabilises cardiac membrane

does NOT lower serum potassium levels

Question 17

insulin/dextrose infusion + nebulised salbutamol in the mx of hyperkalaemia

Answer 17

short term shift in potassium from extracellular to intracellular compartment

Question 18

how is potassium removed from the body in hyperkalaemia

Answer 18

calcium resonium (orally or enema)
- enemas more effective as potassium is secreted in the rectum

loop diuretics

dialysis - should be considered for patients with AKI with persistent hyperkalaemia

Question 19

is hyperkalaemia assoc with acidosis or alkalosis

Answer 19

hyperkalaemia = acidosis

(possium + hydrogen are competitors, as potassium rises, fewer H+ can enter cells)

Question 20

causes of hypOkalaemia where alkalosis is also present

Answer 20

vomiting
thiazide + loop diuretics
cushings syndrome
Conns -> hyperaldosteronism

Question 21

causes of hypOkalaemia where acidosis is also present

Answer 21

diarrhoea
renal tubular acidosis
acetazolamide
partially treated ketoacidosis

Question 22

how does magnesium deficiency affect potassium

Answer 22

hypokalaemia
- normalising potassium may be difficult until magnesium def has been corrected

Question 23

causes of hypernatraemia

Answer 23

dehydration
diabetes insipidus
excess IV saline

osmotic diuresis - hyperosmolar non-ketotic diabetic coma

Question 24

why should hypernatraemia be treated with caution

Answer 24

cerebral oedema - seizures, coma, death

correct suuuuper slowly
- rapid correction may result in demyelination syndrome

(untreated hyponatraemia may also cause cerebral oedema)

Question 25

causes of hyponatraemia where urinary sodium >20

Answer 25

Na depletion, renal loss (hypovolaemic) - diuretics - loop,thiazides - Addisons euvolaemic - SIADH - hypothyroidism

Question 26

causes of hyponatraemia where urinary sodium <20

Answer 26

sodium depletion, extra renal loss - diarrhoea, vomiting, sweating - burns water excess (oedematous) - heart failure, liver cirrhosis - nephrotic syndrome - IV dextrose - psychogenic polydipsia

Question 27

what could cause a false hyponatraemia

Answer 27

blood sample was taken from a drip arm

Question 28

osmotic demyelination syndrome

Answer 28

occurs when hyponatraemia is corrected too quickly fx - dysarthria, dysphagia, paraparesis, quadriparesis, seizures, confusion, coma "locked in syndrome" - unable to move or verbally communicate

Question 29

how is acute, severe hyponatraemia managed

Answer 29

<120 / symptomatic hypertonic saline (typically 3% NaCl) (corrects more rapidly than those with chronic hyponatraemia)

Question 30

who should vasopressin/ADH recepter antagonists (vaptans) be avoided in

Answer 30

- those with hypovolaemic hyponatraemia - Liver disease - can be hepatotoxic --> they stimulate thirst receptors leading to the desire to drink free water

Question 31

management of chronic hyponatraemia without severe symptoms

Answer 31

hypovolaemia - normal saline (0.9% NaCl) --> if serum Na falls, think SIADH euvolemic - fluid restrict to 500-1000ml a day - consider - demeclocycline, vaptans hypervolemic - fluid restrict - consider loop diuretics / vaptans

Question 32

hypomagnesaemia causes

Answer 32

diuretics, **PPIs** **alcohol** total parenteral nutrition diarrhoea hypokalaemia/hypercalcaemia presents similar to hyp**O**calcaemia - paraesthesia, tetany, seizures