Sodium and Water Balance Flashcards
How is serum sodium concentration measured?
[Na+] = mmol Na+/1L H2O
What is the reference interval for serum sodium concentration?
135-145mmol/l
Generally, hyponatraemia becauses more serious when sodium levels fall below what level?
<120 mmol/l
A low serum sodium concentration can be caused by which two things?
- Low sodium concentration
- High water concentration
What symptoms may be experienced with hyponatraemia?
- Altered conciousness
- Confusion
- Nausea
- Vomiting
- Fitting
In which two compartments is water present within the body?
- Extracellular fluid (ECF)
- Intracellular fluid (ICF)
The _____cellular fluid volume is much greater than the _____cellular fluid volume
The intracellular fluid volume is much greater than the extracellular fluid volume
Which fluid compartment contains the vast majority of sodium?
ECF
Why is it that the ECF has a far higher sodium content?
Na+/K+ pump activity
Why is it possible to gain or lose a lot of water without suffering from clinical signs?
Gain or loss is spread across a large volume (ICF + ECF)
Effects are therefore “diluted”
Loss of sodium will lead to a loss of what?
Water
How is it possible for the kidneys to regulate water volume in the body?
By either retaining or excreting sodium, water is conserved or lost respectively
How does a low sodium concentration impact the intracellular fluid?
It doesn’t
The ECF is reduced but the ICF remains relatively constant
How does an increased H2O concentration impact the ECF and ICF?
They both increase
How is dehydration and hyponatraemia treated?
Administer sodium
- IV saline in an emergency
- Oral sodium can also be used