Hyponatremia

Hyponatremia:

less than 135

Patho of hyponatremia:

extracellular fluid has too much water vs sodium; it’s too dilute

In hyponatremia, the cells:

swell

Etiology of hyponatremia:

dilutional or depletional

Dilutional hyponatremia:

factors that cause too much water vs Na

Depletional hyponatremia:

factors that cause too much sodium loss causing there to be too much water

Causes of dilutional hyponatremia:

• excessive ADH

• excessive IV dextrose infusions

• hypotonic irrigating solutions

• tap water enemas

• psychogenic polydipsia

• forced excessive water ingestion (abuse, club initiation)

• excessive beer ingestion

• near-drowning in fresh water

• SSRIs

Factors that cause depletional hyponatremia:

• diuretics (thiazides)

• salt-wasting renal disease

• replacement of water but not Na → emesis, diarrhea, gastric suctioning, diaphoresis, burns

What lab values would you see in a pt w/ hyponatremia?

• decreased serum & urine Na

• decreased urine specific gravity and osmolality

What kind of assessment would you do on a pt w/ hyponatremia?

focused neuro; hx and physical exam

S/S of hyponatremia:

• malaise

• anorexia

• nausea

• vomiting

• headache to confusion, lethargy, seizures, and coma

• papilledema (optical nerve swelling)

  • increased HR, decreased BP

Symptom you would see in a pt w/ profound hyponatremia:

fatal cerebral herniation

Medical tx for hyponatremia:

• sodium replacement → admin of Na thru PO, NG tube, or parenteral route - those who can’t eat will receive LR or an isotonic solution (0.9%)

• water restriction → fluid restriction

  • if severe or pts who have had a TBI → sm amount of hypertonic solution is given to correct cerebral edema (super careful admin required)

Serum Na cannot increase more than:

12 mEq/L in 12 hours

Daily adult Na requirement:

100 mEq/L