Hyponatraemia Flashcards
1
Q
What are some causes of hyponatraemia?
A
Most common
- Administration of hypotonic fluids (eg 0.18% Na)
- Conditions with impaired free water secretion and high ADH levels eg sepsis, meningitis, surgery
- Relative fluid intake excess in patients taking exogenous ADH
- GI loss
Less Common
- Adrenal insufficiency
- Defect in renal tubular absorption
- Psychogenic polydipsia
2
Q
What is the definition of hyponatraemia?
A
Serum Na less than 135mmol/L
3
Q
When do symptoms occur usually? What are some?
A
When Na is less than 125mmol/L
- Headache
- Lethargy, irritibility
- Nausea, vomiting
- Hyporeflexia
- Seizures
- Reduced conscious state
4
Q
How else do you assess hyponatraemia?
A
Assess volume state on examination
Other investigations:
Serum creatinine, K, glucose, urea, chloride
Urine osmolarity and Na
5
Q
How do you manage hyponatraemia
A
If symptomatic - Seizures and CNS depression
- ICU referral, 4ml/kg 3% Na solution until Na is 125 and above
- Intravenous anti-convulsants as clinically indicated
If not symptomatic
- Depending on fluid status either restrict water intake (if euvolaemic) or use normal maintenance fluids (if dehydrated)
6
Q
What is the maximum rate of correction of hyponatraemia? Why?
A
8mmol/L over 24hours
Risk of cerebral pontine demyelination
