Hyper/Hypokalaemia

Question 1

Normal range of potassium.

Answer 1

3.5 - 5.3

Question 2

Causes of hyperkalaemia.

Answer 2

Can be divided into decreased excretion of potassium.

Increased release from cells

Increased extraneous load

Spurious

Question 3

Give causes of hyperkalaemia due to decreased excretion.

Answer 3

AKI

Drugs like amiloride, spironolactone, ACEi, NSAIDs, ciclosporin, ARBs, LMWH, trimethoprin, digoxin, beta-blockers.

Aldosterone deficiency (T4RTA)

Addison’s

Acidosis

Gordon’s syndrome

Hyporeninaemic hypoaldosteronism

Question 4

Give causes of hyperkalaemia due to increased release from cells.

Answer 4

Acidosis

DKA

Rhabdomyolysis/tissue damage

Tumour lysis

Succinylcholine

Digoxin poisoning

Vigorous exercise

Question 5

Give spurious causes of hyperkalaemia.

Answer 5

Leukaemia

Infectious mononucleosis

Thrombocytosis

Haemolysis

Leucocytosis

Question 6

Give other causes of hyperkalaemia.

Answer 6

Hypochloraemic acidosis

Reduced GFR

Acute GN nephritis

TIN/sickle cell

Lupus nephritis

Question 7

Common causes of hyperkalaemia according to Oxford Handbook.

Answer 7

Oliguric renal failure

K+ sparing diuretics

Rhabdomyolysis

DKA

Excess K+ therapy

Addison’s

Massive blood transfusion

Burns

ACEi

Question 8

Treatment of non-urgent hyperkalaemia.

Answer 8

Calcium resonium 15g/8h to bind K+ in the gut

If there is vomiting give the calcium resonium as an enema.

Question 9

ECG changes seen in hyperkalaemia

Answer 9

Tented T waves

Prolonged QRS

Prolonged PR interval

Slurring of ST segment

Loss of p waves

Asystole

Question 10

What is acute severe hyperkalaemia?

Answer 10

> 6.5 mmol/L or any with ECG changes of hyperkalaemia.

Question 11

Treatment of acute severe hyperkalaemia.

Answer 11

If you see it on ECG don’t wait for lab results, just use the blood gas analyser.

1 - 10ml of 10% calcium chloride or 30 ml of 10% calcium gluconate. This is given IV over 5-10 minutes.
It is done to stabilise the myocardium and prevent arrhythmias. If ECG changes persist - repeat treatment.

2 - IV insulin (10u) actrapid in 25g glucose (50ml of 50%).
You can also give sodium bicarbonate 500 mls of 1.4% but it is only effective at driving potassium intracellularly if the patient is acidotic.

3 - Salbutamol 10-20mg via nebuliser. Contraindicated in tachycardia.

4 - Definitive treatment requires K+ removal done by calcium resonium 15-45g orally or rectally.
Furosemide can be given 20-80mg depending on hydration status.

5 - If everything fails dialysis.

Question 12

Signs and symptoms of hyperkalaemia.

Answer 12

Muscle weakness.

Numbness and tingling.

Nausea and vomiting.

Irregular heartbeat.

Shortness of breath.

But usually asymptomatic

Question 13

Signs and symptoms of hypokalaemia.

Answer 13

Fatigue

Constipation

Muscle weakness

Paralysis

Hypotonia

Hyporeflexia

Cramps

Tetany

Palpitations

Light-headedness

Cardiac arrhythmias

Hypertension

Question 14

Causes of hypokalaemia.

Answer 14

Divided into:

Increased renal excretion

Increased aldosterone secretion

Exogenous mineralcorticoids

Renal disease

Reduced intake of K+

Redistribution into cells

GI losses

Question 15

Increased renal excretion causes of hypokalaemia.

Answer 15

Diuretics such as thiazides and loop diuretics.

Question 16

Increased aldosterone secretion causes of hypokalaemia.

Answer 16

Liver failure

Heart failure

Nephrotic syndrome

Cushing’s

Conn’s

ACTH producing tumour

Question 17

Exogenous mineralcorticoid causes of hypokalaemia.

Answer 17

Corticosteroids

Liquorice

Question 18

Renal disease causes of hypokalaemia.

Answer 18

Renal tubular acidosis 1 and 2

Renal tubular damage

Acute leukaemia

Nephrotoxicity by amphotericin, aminoglycosides and cytotoxic drugs.

Bartter’s, Liddle’s, Gitelman’s

Question 19

Reduced intake of K+ causes of hypokalaemia.

Answer 19

IV fluids without K+

Dietary def.

Question 20

Redistribution into cells causes of hypokalaemia

Answer 20

B agonist

Acute MI

Insulin

Megaloblastic anaemia correction

B12 def correction

Alkalosis

Hypokalaemic periodic paralysis

Question 21

GI losses causes of hypokalaemia.

Answer 21

Vomiting

Severe diarrhoea

VIPoma

Zollinger-Ellison

Ileostomy

Enteric fistula

Question 22

Common causes of hypokalaemia according to Oxford handbook.

Answer 22

Diuretics

Vomiting and diarrhoea

Pyloric stenosis

Rectal villous adenoma

Intestinal fistula

Cushings/steroids/ACTH

Conn’s

Alkalosis

Purgative and liquorice abuse

Renal tubular failure

Question 23

ECG changes in hypokalaemia.

Answer 23

Small or inverted T waves

Prominent U waves

Long PR interval

Depressed ST segment

Question 24

Treatment of mild hypokalaemia ( > 2.5 mmol/L and no symptoms)

Answer 24

Oral K+ (Sando-K 2 tabs/8h)

Review K+ after 3 days.

If taking a thiazide consider switching to a K+ sparing diuretic.

Question 25

Treatment of severe hypokalaemia ( < 2.5 mmol/L and/or dangerous symptoms)

Answer 25

Give IV potassium cautiously.

Not more than 20 mmol/h and not more concentrated than 40 mmol/L.

Do not give K+ if oliguric.

Never give K+ as a fast stat bolus dose.

Replace magnesium

Question 26

Why should you replace magnesium in hypokalaemia?

Answer 26

Because hypomagnesaemia exacerbates the hypokalaemia by promoting K+ secretion.

Question 27

Investigations done in hyper/hypokalaemia.

Answer 27

Bloods - FBC, U&Es and Mg2+, Ca2+ and PO42-

ECG

VBG

Question 28

Hypokalaemias effect on the heart

Answer 28

Cardiac hyperexcitability

Can cause functional re-entrant loops