hyper and hypo naturemia Flashcards
difference btw effective and ineffective osmoles
give examples for each
Na is the major effective extra-cellular osmolyte (i.e. the substance that affects osmolality)
Urea is an ineffective osmole in the plasma. This means that urea can move freely across cell membranes and therefore does not cause appreciable shifts in water movement between the intracellular and extracellular compartments.
it is actually the regulation of water intake and excretion that is the main determinant of serum sodium concentration and not vice versa.
interesting
What r are 3 important things to consider in any patient with an abnormal serum Na+ level?
- What is the patient’s volume status?
- How much Na+ is being lost in the urine?
- Is the patient symptomatic?
how do u classify low hyponatremia?
lower than 135mmol.
causes of hyponatremia?
loss of NaCl>> diharrea, vomiting,
Overuse of diuretics> inhibit ability of kidney to conserve Na+
Addisons disease> decreased aldosterone secretion> impaired Na reabsorption
hypernatuermia can also be asscoaited w/ excess water retenttion, this dilutes the Na+ in the ECF> hyponaturemia-Overhydration
consequences of hyponaturemia
rapid reduction in plasma Na+ can cause brain edema
heart failure & Na+?
In heart failure u have so much edema> fluid overloaded! why?
mainly bc they have abnormal perfusion
so body tries to compensate by increasing hormone Angi and aldosterone
which causes water reabsorption
The ADH activity basically diluted the Na in the plamsa>> result in hyponatremia.
Syndrome of inappropriate antidiuretic hormone (SIADH)
high release of ADH
more water reabsorbed
this dilutes the other solutes in our blood (Na)
and takes up more space there >
this stops Aldosterone release!
Na stays in the tubules pulls water too
& excreted in pee!
which normalizes the fluid volume int he blood…
shit, our body is removing Na from our blood wa7na a9lan 3ndna LOW Na mn il asas!
causes of SIADH
really anything that messes with ur ADH release
symptoms of SIADH
In heart failure, if u have a low bp, is it approproate for u body to maintain water?
yes
even though these patients with heart failure have abnormal ADH secretion
what drugs can cause hyponaturemia?
- thiazide diuretics,
- selective serotonin reuptake inhibitors (SSRIs),
- proton pump inhibitors,
- angiotensin-converting enzyme (ACE) inhibitors,
- loop diuretics.
PAST L >> got me low on Na…
why would low Na + cause confusion?
due to cerebral edema!
When hyponatremia occurs, the resulting decrease in plasma osmolality causes water movement into the brain cells (astorcytes) in response to the osmotic gradient, thus causing cerebral edema.
explain how u get osmotic demyelination sydrome
acute demyelination seen in the setting of osmotic changes, typically with the rapid correction of hyponatraemia
basically, since water enters brain cells and causes swelling
this process stimulates Na, K & organic solutes out of the brain cell which causes water diffusion out of cells (brains ways of compensating)
when hypertonic solutions r added to rapidly to correct hyponeutremia> this intervention can outpace the brain’s ability to recapture the solutes lost from the cells and may lead to osmotic injury of the neurons that is assciayed with demyekination.
Prolonged hyponatremia followed by rapid sodium correction results in edema.
how can u avoid osmotic demyelination syndrome from occuirng?
it can be avoided by limitng the correction of chronic hyponeutremia to less than 10 to 13 mmol/L in 24 hrs
and less that 18 mmol/L in 48 hrs.
this SLOW rate of correction, premits the brain to recover the lost osmoles
How do u approach a patients with hyponaturemia
we have to do a fluid assessment to check if theres too much fluid or too little fluid.
this will tell us wether or not the patient has low Na bc they they have too much water on them,
or
they have a TRUE loss of Na+
most patients have hyponatremia due to low osmolality>> (diluted)
what do we access next?
what is the most common cause of fluid overload in patients?
patients with heart problems!
If the cause of hyponatremia is NOT due to fluid overload in the blood.
then what do u do?
what do u call this type of naturemia?
look at true losses of Na+
Types of HYponaturemia
