Lecture 11 - Regulation of serum potassium Flashcards
Most abundant ion in intracellular fluid
K+
Normal serum K+
3.5 - 5.3 mmol/L
Excretion of K+
80% kidneys
20% bowel - lost in faeces and sweat
Insulin
Decreases K+ for 6 hours
If given as treatment of hyperkalaemia, give glucose to avoid hypoglycaemia
How to remove K+
Increase urinary excretion
Dialysis
What foods are high in potassium?
Dark chocolate
Potatoes
Bananas
Tomatoes
High K+ diet
Decreases risk of:
- CVD
- Stroke
Better control of blood pressure if normal kidney function
Hyperkalaemia ECG
Tall T wave Long QRS Long PR interval Small or absent P wave Sine wave
Hypokaleamia presentation
2.5- 3 mmol/L: Atrial fibrillation Muscle weakness Muscle cramps Constipation
Less than 2.5 mmol/L:
- Cardiac arrest
What part of the nephron secretes K+
DCT via the Na+/K+ ATPase
Aldosterone
Upregulates Na+/K+ ATPase therefore more K+ is secreted into the lumen
Spironolactone
K+ sparring diuretic as blocks aldosterone activity
Hyperkalaemia causes
AKI - loss of nephrons therefore less K+ secretion
CKD - caused by diabetes and hypertension
Spironolactone (K+ sparing diuretics)
ACE inhibitors
Aldosterone deficiency
Acidosis
Rhabdomyolysis
Treatment of hyperkalaemia
Insulin with glucose - shifts K+ into cells
Salbutamol nebulisers
Calcium - stabilises cardiac membrane potential
Calcium resonium - binds to potassium in the gut to treat constipation
Low K+ diet
Stop causative meds
Furosemide
Dialysis - replace blood
Causes of hypokalaemia
Potassium entering the cells:
- insulin
- alkalosis
- salbutamol
Diarrhoea
Laxatives
Decreased intake
Diuretics - Loop diuretics (furosemide) and thiazide - increases urine flow and K+ secretion
Primary and secondary hyperaldosteronism
