Hyponatremia

Assessment mental status

Orders
Consider central line (for either hypertonic saline or frequent blood draws)
NPO for confusion
Na check q4h (q1-2 if hypertonic saline for severe hypoNa)
CT head? (CNS mets)
Labs: plasma and urine osm, urine sodium

Diagnosis

  1. Is it real
  2. Is water excretion approipriate
  3. Is ADH present? Check volume status

Is It Real?

Check plasma Osm. If low then it is real. If normal or high think uremia, hyperglycemia, mannitol, hyperTG, hyperproteinemia

Is Water Excretion Appropriate?

If urine osm < 100 then it is appropriate. Kidneys are trying to adjust. Consider psychogenic polydipsia or potomania

If urine osm > 100 then ADH is present

 

Is ADH present? Check volume status

If urine osm > 100 ADH is present. Check volume status for differential.

  • Hypovolemic -> Check Urine Na
    • Low Urine Na -> nonrenal
    • High Urine Na -> renal
      • Diuretic
      • adrenal insufficiency
      • cerebral salt wasting
  • Euvolemic
    • Low urine osm
      • again -> polydipsia, reset osmostat
    • High urine osm
      • SIADH
      • renal failure
      • hypothyroidism
      • glucocorticoid deficiency, secondary adrenal insufficiency
  • Hypervolemic (kidney thinks it is underperfused)
    • CHF
    • cirrhosis
    • Nephrotic syndrome

Treatment

Asymptomic consider fluid restriction

Consider hypertonic saline if CNS involvement

Correction factor is men: 0.6, women: 0.5, eElderly men: 0.5, eElderly women: 0.45

Correct by only 10-12 mEq per 24 hours

Can achieve safe rapid correction of 2-4 mEq/L initially with a 100 cc bolus of 3% NS

 

SIADH

patients may need loop diuretic as fluid is given to correct sodium as patient may become volume overloaded

 

 

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Last Updated August 10, 2015