Hyponatremia Flashcards
acute hyponatremia is defined in
drop in Na <24-48 hrs
chronic hyponatremia is defined in
low Na <135 that occurred in >48 hrs
When to use emergency therapy (hypertonic saline) to treat hyponatremia?
Acute hyponatremia - use if symptoms present
Chronic hyponatremia - use if severe symptoms of seizure or coma.
how does post operative hyponatremia happen?
occurs with release of vasopressin related to surgical stress and non electroyte solutions glycin or sorbitol for irrigation or infusion of hypotonic solutions with surgery
When do we see exercise associated hyponatremia?
can be mild and asymptomatic and after endurance events like marathons or triathalone
How does exercise associated hyponatremia happen?
hypotonic fluids during the event with non osmotic release of vasopressin results in renal water retention and hyponatremia.
Treatment of exercise associated hyponatremia?
if severe fluid restrict and give hypertonic saline if severely somatic.
How to prevent exercise associated hyponatremia?
drinking only when thirsty.
However for collapsed athlete may have hypernatremia due to not drinking enough.
HCTZ induced hyponatremia occurs
1-2 weeks post starting drug
seen in older woman with low BMI.
36% of pts on HCTZ had Na <130
pts >70 yrs are 4 times higher risk for hyponatremia
how does thiazide cause hyponatremia?
diuretic works by increasing Na and K excretion in the cortical distal tubule and increasing medullary water reabsorption. Concentrated Urine leads to ADH induced water retention which further dilutes the serum and worsens the hyponatremia.
why doesn’t loop diuretics cause hyponatremia?
They impair medullary water reabsorption and so medulla is less responsive to ADH induced water retention
but does act in loop of Hnle to decrease Na reabsorption and increase excretion.
treatment of HCTZ induced hyponatremia
stop diuretic and replace K.
what medications can cause hyponatremia
HCTZ
oxcarbazepine
PPI - through action of sodium potassium ATP pump
SSRI
