Hyper/Hypokalaemia Flashcards
Normal range of potassium.
3.5 - 5.3
Causes of hyperkalaemia.
Can be divided into decreased excretion of potassium.
Increased release from cells
Increased extraneous load
Spurious
Give causes of hyperkalaemia due to decreased excretion.
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
Give causes of hyperkalaemia due to increased release from cells.
Acidosis
DKA
Rhabdomyolysis/tissue damage
Tumour lysis
Succinylcholine
Digoxin poisoning
Vigorous exercise
Give spurious causes of hyperkalaemia.
Leukaemia
Infectious mononucleosis
Thrombocytosis
Haemolysis
Leucocytosis
Give other causes of hyperkalaemia.
Hypochloraemic acidosis
Reduced GFR
Acute GN nephritis
TIN/sickle cell
Lupus nephritis
Common causes of hyperkalaemia according to Oxford Handbook.
Oliguric renal failure
K+ sparing diuretics
Rhabdomyolysis
DKA
Excess K+ therapy
Addison’s
Massive blood transfusion
Burns
ACEi
Treatment of non-urgent hyperkalaemia.
Calcium resonium 15g/8h to bind K+ in the gut
If there is vomiting give the calcium resonium as an enema.
ECG changes seen in hyperkalaemia
Tented T waves
Prolonged QRS
Prolonged PR interval
Slurring of ST segment
Loss of p waves
Asystole
What is acute severe hyperkalaemia?
> 6.5 mmol/L or any with ECG changes of hyperkalaemia.
Treatment of acute severe hyperkalaemia.
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.
Signs and symptoms of hyperkalaemia.
Muscle weakness.
Numbness and tingling.
Nausea and vomiting.
Irregular heartbeat.
Shortness of breath.
But usually asymptomatic
Signs and symptoms of hypokalaemia.
Fatigue
Constipation
Muscle weakness
Paralysis
Hypotonia
Hyporeflexia
Cramps
Tetany
Palpitations
Light-headedness
Cardiac arrhythmias
Hypertension
Causes of hypokalaemia.
Divided into:
Increased renal excretion
Increased aldosterone secretion
Exogenous mineralcorticoids
Renal disease
Reduced intake of K+
Redistribution into cells
GI losses
Increased renal excretion causes of hypokalaemia.
Diuretics such as thiazides and loop diuretics.
Increased aldosterone secretion causes of hypokalaemia.
Liver failure
Heart failure
Nephrotic syndrome
Cushing’s
Conn’s
ACTH producing tumour
Exogenous mineralcorticoid causes of hypokalaemia.
Corticosteroids
Liquorice
Renal disease causes of hypokalaemia.
Renal tubular acidosis 1 and 2
Renal tubular damage
Acute leukaemia
Nephrotoxicity by amphotericin, aminoglycosides and cytotoxic drugs.
Bartter’s, Liddle’s, Gitelman’s
Reduced intake of K+ causes of hypokalaemia.
IV fluids without K+
Dietary def.
Redistribution into cells causes of hypokalaemia
B agonist
Acute MI
Insulin
Megaloblastic anaemia correction
B12 def correction
Alkalosis
Hypokalaemic periodic paralysis
GI losses causes of hypokalaemia.
Vomiting
Severe diarrhoea
VIPoma
Zollinger-Ellison
Ileostomy
Enteric fistula
Common causes of hypokalaemia according to Oxford handbook.
Diuretics
Vomiting and diarrhoea
Pyloric stenosis
Rectal villous adenoma
Intestinal fistula
Cushings/steroids/ACTH
Conn’s
Alkalosis
Purgative and liquorice abuse
Renal tubular failure
ECG changes in hypokalaemia.
Small or inverted T waves
Prominent U waves
Long PR interval
Depressed ST segment
Treatment of mild hypokalaemia ( > 2.5 mmol/L and no symptoms)
Oral K+ (Sando-K 2 tabs/8h)
Review K+ after 3 days.
If taking a thiazide consider switching to a K+ sparing diuretic.
Treatment of severe hypokalaemia ( < 2.5 mmol/L and/or dangerous symptoms)
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
Why should you replace magnesium in hypokalaemia?
Because hypomagnesaemia exacerbates the hypokalaemia by promoting K+ secretion.
Investigations done in hyper/hypokalaemia.
Bloods - FBC, U&Es and Mg2+, Ca2+ and PO42-
ECG
VBG
Hypokalaemias effect on the heart
Cardiac hyperexcitability
Can cause functional re-entrant loops
