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What is hyponatremia?
Na <135
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What is severe hyponatremia?
Na < 120-125
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What are sx of hyponatremia, and at what Na level do you start to see them?
- Confusion, N/V, seizure, obtundation
- See at <120
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What labs do you order for someone who is hyponatremic?
- Serum osm
- Urine osm
- Urine Na
- Urine Cr
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What is the most common form of hyponatremia?
Hypotonic hyponatremia
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What is hypotonic hyponatremia?
- Excess of water relative to Na
- serum osm <280
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What is isotonic hyponatremia?
- Rare, lab artifact, possible from hyperproteinemia and HL
- serum Osm is 280-285
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What is hypertonic hyponatremia?
- Result of another osmole like glucose or mannitol drawing water extracellularly?
- serum OSM >295
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How do you tx acute sxmatic hyponatremia?
- Correct at rate of 2mEq/L/h for the first 2-3 hours until sx resolve using hypertonic saline (3%)
- Do not correct more than 10-12 mEq in 24 hours
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How do you tx acute asx hyponatremia?
- Correct at a rate of 0.5 mEg/L/hr
- Do not correct more than 10-12 mEq in 24 hours
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What happens if you correct hyponatremia too fast?
Central pontine myelinolysis
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How do you tx hypovolemic hyponatremia?
Replete volume with NSS
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What causes euvolemic hyponatremia?
- SIADH
- hypothyroidism
- Adrenal insufficiency
- Primary polydipsia
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What causes hypervolemic hyponatremia?
- Cirrhosis
- CHF
- Renal failure
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What causes hypovolemic hyponatremia?
- Renal loss (ie diuretics)
- Mineralcorticoid deficiency
- Extra-renal loss
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How do you tx euvolemic hyponatremia caused by SIADH?
- Free water restriction, tx underlying cause, possible Tolvaptan but consult nephrology first
- DO NOT USE NSS
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How do you tx hypervolemic hyponatremia?
- restrict free water
- Lasix in CHF
- colloid infusions in cirrhotics
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