hypokalaemia/hyperkalaemia

Question 1

primary hyperaldosteronism

Answer 1

conn’s syndrome
adrenals produce too much aldosterone
due to either
1. adrenal adenoma (most common)
2. bilateral adrenal hyperplasia
3. familial hyperaldosteronism
4. adrenal carcinoma

Question 2

secondary hyperaldosteronism

Answer 2

excessive renin stimulates production of aldosterone
usually because the blood pressure in the kidney is disproportionately higher than in the rest of the body which may be due to
1. renal artery stenosis
2. renal artery obstruction
3. heart failure

Question 3

renal artery stenosis

Answer 3

narrowing of the renal artery
found in patients with atherosclerosis
confirmed with doppler US, CTA or MRA

Question 4

how to tell if someone has primary or secondary hyperaldosteronism

Answer 4

renin will be low in someone with primary hyperaldosteronism, but high in secondary
check renin:aldosterone ratio

Question 5

Investigations for hyperaldosteronism

Answer 5

renin:angiotensin ratio to determine if primary or secondary
blood pressure, likely to be high
electrolytes, hypokalaemia
blood gas, alkalosis

Question 6

some causes of low serum potassium concentration

Answer 6

increased urine loss eg. diuretic use
excessive GI loss eg. vomiting, diarrhoea, laxative use
decreased intake ie. poor nutrition
hyperaldosteronism
potassium shift into cells eg. metabolic alkalosis

Question 7

what do principal cells do

Answer 7

resorb sodium and excrete potassium in response to aldosterone

Question 8

what do intercalated cells do

Answer 8

resorb potassium and secrete H+ in response to aldosterone, or low serum K

Question 9

ECG changes due to hyperkalaemia

Answer 9

peaked T waves and broadened QRS complex

Question 10

caauses of hyperkalaemia

Answer 10

pseudohyperkalaemia
kidney failure
fluid volume depletion
hypoaldosteronism
drug induced
increased potassium release from cells eg. metabolic acidosis, insulin deficiency, rhabdomyolysis