EMCrit Podcast 39 – Hyponatremia

Hmm… he’s tasty, but he just needs a little salt

In this podcast, I discuss the management of hyponatremia in the ED. After reading countless articles from the nephrology literature…I can still attest that I have not a friggin’ clue about renal physiology. But I think I have found a simpler path to the work-up and treatment of low sodium in the ED.

When they are <130 is when I get a little worried

Step I-Send Lots of Labs

Here is what you need:

Serum-electrolytes, osmolality, uric acid (if on diuretics), and you might as well send a TSH and cortisol as well (if you have any suspicion of an endocrine cause)

Urine-UA, urine lytes, urine urea, urine uric acid (if on diuretics), urine osm, urine creatinine

Want to learn more about FENa and FEUrea? Well I have an article for you.

Step II-Treat CNS dysfunction

If the patient is altered, comatose, seizing, or has neurologic findings, then raise the sodium by a little bit

Give 3% saline, 100 ml over 10-60 minutes (2 cc/kg up to a max of 100 cc)

10 minutes later, may repeat X 1

may be given peripherally through any reasonable IV

each 100 ml will raise sodium by ~2 mmol/l

Step III-Hang tight

Do not feel the need to do anything else, just fluid restrict the patient

Place a foley

Do not feel tempted to give NS

Do not be clever, just fluid restrict and admit.

Patients are at a fall risk with hyponatremia

Get a CT scan if they are still a little wacky

Remember the rules of 6’s (from the Stern article below)

Be incredibly careful when correcting hypokalemia, potassium repletion will raise the Na

Step IV-What to do when you couldn’t follow step III

dDAVP 1-2 mcg IV or SubQ x 1

Consult renal

Consider D5W 6ml/kg over 1 hour in consultation with renal if you have really screwed up

For more on this, see the Emergency Pharm D Blog

Articles

Read this excellent case report from Stern

Excellent Review by Schrier (Curr Opin Crit Care 2008;14:627)
Review of Drug-Induced Hyponatremia (Am J Kidney Dis 2008;52:144)
Understanding Lab Testing for Hyponatremia (Clin J Am Soc Nephrol 2008;3:1175)
The hyponatremia formulas do not work so well (Clin J Am Soc Nephrol 2007;2:1110 and Nephrol Dial Transplant 2006;21:1564)