L2: Disorders of Sodium Balance Flashcards
What is the range of normal sodium levels in the body?
[135 - 145] mmol/L or mEq/L
What is considered hyponatraemia? (value)
Na+ < 135 mEq/L
Why is there a reduction in Na+ in hyperglycaemic states?
- increase in blood glucose
- water drawn extracellularly
- water dilutes blood
- reduction in electrolytes
What are 2 causes of pseudohyponatraemia?
- Increased Proteins/Lipids
2. Hyperglycaemia
What is the function of anti-diuretic hormone?
- retains water
- adds aquaporin channels in collecting duct to reabsorb water
How much water can you safely drink in a day?
14 Litres
What is another name for MDMA (drug)?
Ecstasy
What are 5 major causes of SIADH?
- MDMA
- Neurological
- Pulmonary Disease (e.g. lung cancer, TB)
- Stress (e.g. pain, vomiting…)
- Medication (e.g. antipsychotics, SSRI…)
If hyponatraemia is corrected too quickly, what can happen to the brain?
Osmotic Demyelination
How is an uncompensated, severely symptomatic patient with hyponatraemia (in the brain) treated?
3% Saline Bolus (150 mL over 20 mins)
How is an uncompensated, mildly symptomatic patient with hyponatraemia (in the brain) treated?
0.9% Saline
How is a compensated, asymptomatic patient with hyponatraemia (in the brain) treated?
Water Restriction
Treat Volume Disorder
Increased Solute Intake (w/ a dietician)
± Loop Diuretics + NaCl
What is considered hypernatraemia? (value)
Na+ > 145 mEq/L
What is the commonest presentation/cause of hypernatraemia?
- fluid deprivation in patients who cannot perceive, respond to or communicate their thirst
- elderly or cognitively impaired patients
Is hyponatraemia or hypernatraemia more common?
Hyponatraemia
