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, LFTs, 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


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)

Fantastic Review Article on Hyponatremia and SIADH

You finished the 'cast,
Now get CME credit

Already an EMCrit CME Subscriber?
Click Here to Get CME Credit for the Episode

Not a subcriber yet? Why the heck not?
By subscribing, you can...

  • Get CME hours
  • Support the show
  • Write it off on your taxes or get reimbursed by your department

Sign Up Today!


Subscribe Now

If you enjoyed this post, you will almost certainly enjoy our others. Subscribe to our email list to keep informed on all of the ED Critical Care goodness.

This Post was by , MD, published 5 years ago. We never spam; we hate spammers! Spammers probably work for the Joint Commission.


  1. mark albert says

    Scott, Desmopressin (DDVAP), frequently used for nocturnal enuresis, Diabetic isipibitus and a certain type of Hemophilia in outpatient setting in a nasal formulation has a potential to cause hyponatremia.I am curious, in this acute setting. did you come across the mechanism of action? Excellent as always presentation!!!!

    • emcrit says

      DDAVP is basically synthetic ADH (anit-diuretic hormone) without the vasopressor effects of vasopressin, so this drug just turns off the dilute urine production–more water retained, stabilization or slight drop in the sodium.

      • lota says

        hey scott,

        just wanted to say ur awesome for doing what you do and that you do it very well. and thanks for doing all this for free

      • says

        I’ve described an interesting case of desmopressin-induced hyponatremia with significant neurological symptoms at a sodium level of only 125 mmol/L on LITFL: http://lifeinthefastlane.com/2010/03/laboratory-tester-003/ Some of my collegues were relectant to treat the hyponatremia – but the patient rapidly improved during hypertonic saline administration (then later on had a massive diuresis resulting in a big jump in Na… but that’s OK, it was acute).

        Overall, I think your approach is in keeping with my own limited understanding of hyponatremia… My one big piece of advice, to reiterate your own recommendations, is don’t be afraid of hypertonic saline – if your patient has seizures, altered mental state or coma (or even acute pulmonary edema in the setting of hyponatremia) , give it! I like the rule of 3?s: 3mL/kg of 3% NaCl over 30 mins (should raise Na by about 4 mmol – approx equivalent to 2 of your 100mL boluses in an adult) – also, if the patient gets better… you can just stop the infusion!

        • emcrit says

          Love your Rule of 3s and it divides so nicely into the rules of 6s and so easy to remember.

          So in a symptomatic patient you want 3 mls/kg over the first 30 minutes. Give half over 10 minutes; wait 10 minutes, give the other half over 10 minutes.


          Give 3 ml/kg of 3% over 30 minutes, stop if the patient’s mental status improves.

          Love it!

  2. couch says

    Great podcast!
    I don’t really understand the reasoning for the cortisol. Wouldn’t this be the one test in your list that the floor team could do in the early morning hours the next day if it is still in the differential? I can’t think of any confounding effect of the ED treatment.
    I don’t know the exact pretest probability of adrenal insufficiency in a patient with hyponatremia in the ED, but in my experience it is uncommon. Sending a cortisol on every patient with hyponatremia, even if a common diagnosis such as thiazide induced hyponatremia is very likely, isn’t really cheap either.
    Totally different story of course if patient presents in a clinical state that could be acute adrenal crisis.

    • emcrit says

      agree absolutely. I think I said if you have clinical suspicion for adrenal insufficiency on the podcast and then followed with a clinical-acumen ruining comment that if you can’t bother to think this through, just send it. But you are absolutely right, we should strive to be good, not accept that we are sometimes bad–so corotisol only when you suspect adrenal insuff.

  3. says

    Agree with couch–probably if you have a good story for adrenal insufficiency, or at least hyponatremia and hyperkalemia, it would make sense, but that seems like a lot of cortisol levels.

    I also find that these patients come in, looking dry, and before you even get the sodium back, you’ve given them a liter of fluid. I don’t typically hear about bad outcomes after this.

    Also, I was curious what the actual incidence of osmotic demyelination is — I had heard that despite all our concern about sodium correction rates, it’s still pretty rare.

    I have a calculator for less aggressive repletion rates on MDCalc.

    • emcrit says

      despite repeated searching, i can’t find a good estimate of how frequently osm. demyelination occurs. Most articles just quote how many times it has been reported in the literature.

      I don’t think you will hear of bad outcomes until you have one, which may be once in your whole career. Most of these patients are not profoundly dehydrated so 1 liter of saline won’t do anything to their sodium.

      The calculator on the excellent MDCalc site relies on the Androgue Madias formula mentioned in the podcast. This formula will be inaccurate if the patient suddenly starts putting out a ton of urine. Two of quite a few refs are in the show notes.

  4. couch says

    Thanks Scott, now I totally agree! A quote from a book (ISBN 9781416024422):
    (shortened) “appart form the rapid rise in P-Na due to a large water diuresis (wich can be due to increase of distal delivery of filtrate in volume depleted patients OR disappearence of ADH action in SIADH patients) the other major risk factors for developing osmotic demyelination are K+ depletion or/and malnourishment. Thus extreme care should be taken in such patients and the maximum rate of P-Na rise should be less (maximum level, not target level) than 4mmol/L/24h. If water diuresis should occur or the P-Na has risen by 4mmol, dDAVP administration is indicated.”
    Thus, one might consider even a lower rate of correction in patients like that, and use the 6mmol/24h in all other patients. I cannot comment on the evidence of this recommendation.

    • emcrit says

      Here are the risks listed in the Stern article:
      ? Chronic hyponatremia
      ? Serum sodium concentration <105 mEq/L
      ? Hypokalemia
      ? Alcoholism
      ? Malnutrition
      ? Liver disease
      I think in the ED, just as you mention, the slower the better once the dangerous symptoms have been treated.

  5. Shawn says

    What if the hypertonic saline isn’t readily available in the ED? And the pharmacist is on break/lunch/administrative leave… What about using 7.5% sodium bicarb? Just a thought.

    • emcrit says

      It is my feeling that 50 ml of sodium bicarbonate will work fine, but to my knowledge, no one has studied it for this use.

      • says

        There is a paper supporting the use of bicarb for treating high ICPs:

        Volume 13, Number 1, 24-28, DOI: 10.1007/s12028-010-9368-8
        Sodium Bicarbonate Lowers Intracranial Pressure After Traumatic Brain Injury
        Chris Bourdeaux and Jules Brown

        Published online: 27 April 2010

        Hypertonic saline is routinely used to treat rises in intracranial pressure (ICP) post-traumatic head injury. Repeated doses often cause a hyperchloremic metabolic acidosis. We investigated the efficacy of 8.4% sodium bicarbonate as an alternative method of lowering ICP without generating a metabolic acidosis.

        We prospectively studied 10 episodes of unprovoked ICP rise in 7 patients treated with 85 ml of 8.4% sodium bicarbonate in place of our usual 100 ml 5% saline. We measured ICP and mean arterial pressure continuously for 6 h after infusion. Serum pH, pCO2, [Na+], and [Cl?] were measured at baseline, 30 min, 60 min and then hourly for 6 h.

        At the completion of the infusion (t = 30 min), the mean ICP fell from 28.5 mmHg (±2.62) to 10.33 mmHg (±1.89),P < 0.01. Mean ICP remained below 20 mmHg at all time points for 6 h. Mean arterial pressure was unchanged leading to an increased cerebral perfusion pressure at all time points for 6 h post-infusion. pH was elevated from 7.45 ± 0.05 at baseline to 7.50 ± 0.05, P < 0.01 at t = 30 min, and remained elevated. Serum [Na+] increased from 145.4 ± 6.02 to 147.1 ± 6.3 mmol/l, P < 0.01 at t = 30 min. pCO2 did not change.

        A single dose of 8.4% sodium bicarbonate is effective at treating rises in ICP for at least 6 h. Serum sodium was raised but without generation of a hyperchloremic metabolic acidosis.


      • hafeez says

        Well iam resident in nephrology and my consyltant treated an elderly male with 300ml of sodabicarb and 700 ml of d5w infusion.Next his sodium was improved by around 10 meq,He has given me the task for finding the logic for above treatment.I think soda bicarb also works fine

      • David Seiwell says

        Scott I know this was an old article so I’m not sure you will even see this, but I had a case a couple of nights ago and relistened to your pod on this subject. I’m a flight nurse and my patients NA was I think 132 and it was a lab from early that morning and I was taking care of her at night. Her mentation stated to decrease some and I was suspecting the NA to be the cause. I was just woundering if there is a way to mix that 3% in the air? It was good info to find this for the bicarb. Not sure if I would use anything unless the patient started to have active seizures

  6. don zweig says

    As usual fantastic and practicle!! Thanks. I think you said 6cc of d5w instead of 6cc/kg in your talk.


  7. Dear Patrick Cheah says

    great podcasts … learn a lot from you…
    I have never treat patient with two bolus of 100cc 3%NS. do you do this in seizure pt only or Na down to what level ?

    ED physcian in Taiwan

    • Dr Ashs says

      but indicated Na Rise even in severe hyponatremia in 3hrs should be not more than 4 mmol/ l only …..?????

  8. Floyd says

    Hey scott, I am a field paramedic. What symptoms would lead you to think hyponatremia without labs, and what would be the best prehospital treatment? thank you for any replies.

  9. Swedan says

    5 stars.
    How many patients did I srew?. But I am sure your presentation will make me help patients.

  10. JLM says

    Scott, how many (if any) bad cases have you seen from SSRI’s? I know you mentioned the number #1 cause, thiazides but I have heard the SSRI’s can be culprits in SIADH.


  11. Joe Lang says

    Enjoyed the talk. Do you have a protocol set up for hypertonic saline to be given via peripheral IV? I recently had a young patient with a sodium of 114 and a seizure. My pharmacy would not release hypertonic saline to me until a central line was in. Their logic was the osmolarity of the infusion was too high to even do 25 cc/hr of 3%.

  12. Hassan Almaateeq says

    Thanks Emcrit.. wonderfull,concise thoughts
    yesterday i came across one lady who developed seizure secondary to Na of 113.. 3% NaCl started by medical with v.low dose 60 ml over 3hrs.. later patient developed large urine diuresis (7 Litres).!! & Na rised to 125… fortunately patient did well

  13. Lakshay says

    Great podcast Scott.. as usual
    My colleagues still stick to that Normal Saline, irrespective of the CNS symptoms..It gets very frustrating for me sometimes when I see a Na of 114 coming with seizures and 3% Saline is not given. I have been giving 3% saline via peripheral IV for 2 years now and trust me I have not seen even a single screwed up case..
    Hope this podcast will bring in some changes


  14. Lakshay says

    Great podcast Scott.. as usual
    My colleagues still stick to that Normal Saline, irrespective of the CNS symptoms..It gets very frustrating for me sometimes when I see a Na of 114 coming with seizures and 3% Saline is not given. I have been giving 3% saline via peripheral IV for 2 years now and trust me I have not seen even a single screwed up case..
    Hope this podcast will bring in some changes

  15. Melissa says

    Hi Scott,

    Wondering if you have a link to the reference giving 7.5% saline peripherally.

    Thanks in advance!

  16. Jill Logan, PharmD says

    Hi Scott,

    Another good argument to give 3% NaCl peripherally is the Osms are about the same as PPN.



      • Winston King, CRNA says

        Thoroughly enjoyed the pod cast and the references.

        Not sure if the thread is still active, but had a case of severe hyponatremia in an 89 year old after TURP procedure while on medical mission trip to Central America. We had no hypertonic saline and patient’s sodium was 105 and he was comatose. I suggested Sodium Bicarbonate and we gave 1/2 amp IV slowly. We put potassium in his IV and gave slowly. We restricted his fluids, gathered his family around him and had a prayer. One final suggestion was to place an NG tube and give some salt brine, so we mixed several teaspoons of table salt in several ounces of water and placed it down the tube. To our amazement, he regained consciousness the next morning, recognized his family and was taking nourishment midday, and his sodium levels had noramlized 48 hours later and he was discharged. Came back 7 days later for postop visit and had no neurologic deficit and felt fine. Aware of the dangers of rapid overcorrection, we were amazed he survived neurologically intact.


    reading the talk, again and again.. still learning lot of points here
    yesterday one patient with history recent start of thiazide for HTN, history of alcohol consumption, brought with delirium, agitation.. Na 105, Cl 62 K 4 HCO3 24 Ph 7.45
    due to lack of ICU resources we were trying to give boluses of Diazepam
    received 10 ml of 3% NaCl + 500ml of 0.9% NaCl (this was random thoughts before trying to review the ideal dose).. repeated Na came 109 Cl 63 (after 4 hours)
    I wonder if we administered 100ml of 3% NaCl, what will be the rate of correction?!
    100 ml of 3% saline (5meq) + 500ml of NS (75meq) total 80 meq .. Vs the 100ml of 3% (50meq)
    seems traditional 0;9% saline boluses has higher amount of sodium!! i ‘m not sure how that wouldn’t work??


      correction :———-
      10 ml of 3% saline (5meq) + 500ml of NS (75meq) total 80 meq .. Vs the 100ml of 3% (50meq)
      seems traditional 0;9% saline boluses has higher amount of sodium!! i ‘m not sure how that wouldn’t work??

  18. Sebastian says

    Hi Scott,
    First and foremost, your awesome. Im a resident a UCSD and setting up a journal club soon. Playing with the idea of a few hyponatremia articles. I know you state the review by Schreir is excellent, just curious if you knew of any other articles that had came out in the last 3 years.
    Take care,

  19. Argo says

    Bravo! I enjoyed a lot listening to your podcast. Thank you Scott for sharing your knowledge. :)


Speak Your Mind (Along with your name, job, and affiliation)