How is [Na+] calculated?
[Na+] = mmol Na+ / L H2O
What is the reference range of [Na+]?
135 - 145 mmol/L
What level of Na+ indicates hyponatraemia?
< 120 mmol/L
What are the two possible mechanisms of hyponatraemia?
Decrease in [Na+]
Increase in [H2O]
___ follows sodium everywhere it goes.
What are the symptoms of hyponatraemia caused by a decrease in sodium concentration?
Dry mucuous membranes
Reduced urine output
Decreased level of consciousness
What is the main symptom of hyponatraemia due to increase in water concentration?
Increase in ECF and ICF volume, producing peripheral oedema
The volume of the ECF is ___ the volume of the ICF.
The volume of the ICF is ___ the volume of the ECF.
In terms of the ICF and ECF, where is
b) sodium found?
a) Water is found in both ECF and ICF
b) Sodium is only found in ECF (by action of sodium-potassium pump)
How are the two types of hyponatraemia treated?
Too much water ⇒ Fluid restrict
Too little sodium ⇒ Give sodium
How is sodium homeostasis maintained?
Which gland produces mineralocorticoids like aldosterone?
Zona glomerulosa of the adrenal cortex
How do mineralocorticoids maintain sodium homeostasis?
Cause sodium reabsorption in the distal convoluted tubules of the kidneys
Which mineralocorticoid causes sodium retention in response to hypotension?
What happens when mineralocorticoids are produced in excess?
Sodium retention > Water retention > Hypernatraemia/volaemia
What happens when mineralocorticoids are deficient?
Sodium loss > Water loss > Hyponatraemia/volaemia
How is water homeostasis maintained?
Which gland secretes ADH?
How does ADH maintain water homeostasis?
Promotes water reabsorption in the collecting ducts of the kidneys
What is the concentration of urine also known as?
ADH excess produces ___ urine and therefore a (high/low) urine osmolality.
high urine osmolality
ADH deficiency produces ___ urine and therefore a (high / low) urine osmolality.
low urine osmolality
What condition causes ADH excess, excess water reabsorption and hyponatraemia?
What level of Na+ indicates hypernatraemia?
> 160 mmol/L
What can cause an increase in sodium levels leading to hypernatreamia?
What can cause water loss leading to hypernatraemia?
Profuse vomiting (e.g DKA)
Inadequate H2O intake
How is water loss hypernatreamia treated?
How is hypernatraemia caused by sodium excess treated?
(To cause natriuresis)