Electrolyte abnormalities Flashcards
What is main cause of hypernatraemia
HYPOVOLAEMIC: DEHYDRATION
- elderly and not drinking sufficiently
- GI loss / sweat loss
- diabetes insipidus
if euvolaemic > increase in sodium:
- Medical high intake (hypertonic saline, sodium bicarb)
- Conns
- RAS
How do you manage hypernatramemia
IV DEXTROSE 5% 1L/6-8h
remember serial sodium measurements every 6h - make sure it is dropping at MAX rate of 0.5 mmol/hour
What are compolications of hypernatraemia
rapid correction: cerebral oedema
How do you manage HYPOnatraemia
HYPOVOLAEMIC
- dehydrated > give 0.9% NaCl
EUVOLAEMIC/HYPERVOLAEMIC
- fluid restrict (e.g. 500ml per day) + treat underlying cause
What is a danger in correcting hyponatraemia top quickly
cerebral pontine myelinolysis
What are hyperkalaemic changes on ECG
Tall and tented T waves
Broad QRS
Flat P wave
Prolonged PR interval (bradycardia)
What are symptoms of hyperkalaemia
muscle weakness and cramps
paraesthesia
causes of hyperkalaemia
Insuff renal K+ excretion
- Low GFR (CKD/AKI)
- Low renin (T4 RTA, NSAIDS)
- ACEi
- ARB
Excess K+ release from cells
- rhabdomyolisis
- acidosis
- burns
Massive blood transfusion
Drugs: K+ sparing diuretics, suxamethonium, ACEi
Metabolic acidosis (DM)
Management of hyperkalaemia
- 30ml 10% calcium gluconate over 10 mins
- 10U Actrapid insulin in 50 mL glucose 50% given over 5-15 minutes
- 5mg salbutamol nebulised STAT
- Treat underlying cause
- Repeat K+ in 6 hours
* * if treatment resistant, discuss with renal team re dialysis
(Updated from NICE BNF Jan 2024)
What are causes of hypokalaemia
EXCESS K+ loss
- GI LOSSES (diarrhoea, vomiting, fistulas)
- RENAL LOSS
K+ drive into cells
- insulin, insulinoma
- alkalosis
How do you manage hypokalaemia
Mild (2.5-3): SandoK BD
- Review after 3 days
Moderate (3-2.5): IV KCl 40mmol /1L / 6hours
Severe (<2.5) IVKCl 40mmol /1L / 4hours
NEVER give K+ as fast stat bolus, max rate 10mmol/hour generally (cardiac monitoring if more)
