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Flashcards in Nephro - Na - Online MedEd Deck (14):

Disorders of Na are actually disorders of __

Na is marker of tonicity of blood and has nothing to do with salt


Blood and cells separated by

Semi-permeable membrane


Hyponatremia - too little Na in blood so...

So H2O will flow from blood to cells
Causes swelling of cells
This is balance out tonicity
Swelling = bad


Hypernatremia - too much Na in blood so...

So H2O will flow from cells to blood
Causes shrinkage of cells
Shrinkage = bad


The degree of symptoms with swelling and shrinkage of cells will depend on....

Rate of Na change
Na change/Time
Acute changes - more symptoms


Symptoms of hypoNa and hyperNa

Mild - asymptomatic
Mod - N/V, confusion, headache
Severe - coma, seizures


How to fix hyperNa

For degrees of Na change
HyperNa = free water deficit = dehydration
Mild - best way is to replace by mouth - oral H2O
Severe - D5W (give hypotonic)
Mod - IVF NS


How to fix hypoNa

Dependent on diagnosis
Severe - hypertonic Na, 3% NaCl (out of danger zone)
Mod - IVF NS
Mild/asymptomatic - need to figure out diagnosis, will be disease specific


Pathophys of hypernatremia to hyponatremia

HyperNa - dehydration/free water deficit
HypoNa - ddx


Hyponatremia - what is the first test to do

Serum osmoles
2xNa + glucose/1.8 + BUN/2.8 = normal is 280
1) Serum osmoles are normal = this is isotonic hyponatremia = pseudohyponatremia
-Caused by lab abnormality (fats and proteins)
-So if serum osmoles are normal, there is no disorder
2) Serum osmoles are elevated - hypertonic hyponatremia
-Something in the equation or something else that is causing hypertonic (glucose, EtOH). So the Na decreases to keep the equation normal
-Happens in diabetic
-For every 100 BG above first 100, need to correct Na by 1.6 (ex. 500 BG, correct Na 4x1.6 = 6.5). If Na is 130 --> now 136.5 by correction
-i.e. give insulin
3) Hypotonic hyponatremia - true hypotonic hyponatremia
-Need Hx and Px to decide volume status
-Volume up - correct Na by diuresis
-Volume down - correct by IVF
-Euvolemic - RATS
-Renal tubular acidosis (urinalysis, lytes), Addison's (cortisol), Thyroid (TSH), SIADH (dx of exclusion)



Volume restriction
Gentle diuresis


Urine sodium should be tested in hypotonic hyponatremia... this is to look at



Urine ormole should be tested in hypotonic hyponatremia... this is to look at



Osmotic demyelination

If correct Na too quickly... may get spastic, quadriplegia
0.25 per hour
need correction of 4-6 on first day to alleviated symptoms
exception: to stop seizure