- 35 yo F with no PMH BIBEMS for generalized seizure on day of presentation
- No history of seizures
- Lasted for 1 minute and resolved prior to EMS arrival
- No fevers, N/V/D, SOB, CP per collateral
Medications: None
Neuro: PERRL, opening eyes spontaneously but not interactive, nonverbal, moving all extremities
- Acute (<24 hrs)
- Chronic (>24 hrs)
- Mild: Na 130-135
- Moderate: Na 121-129
- Severe: <120
- Typically absent in chronic hyponatremia if Na >120
- Mild-Mod
- HA, N/V, fatigue, gait, confusion
- Severe
- Seizures, obtundation, coma, respiratory arrest
- Hypovolemic
- d/t GI or renal lossess
- Normovolemia
- SIADH, polydipsia
- Hypervolemia
- Heart failure, cirrhosis
- NB: Normal response would be to produce urine with Na <10 mEq/L
- SIADH
- Hypothyroidism
- Adrenal insufficiency
- Osmotic diuresis
- Diuretics
- Renal failure
- Treat those with Na <115 mEq/L or when patient is symptomatic
- Urine lytes only useful before starting treatment
- Use hypertonic 3% saline in:
- Na <120 mEq/L
- Rapidly developed (>0.5 mEq/L decrease per hours)
- a/w coma or seizure
- Goal increase: 6 mEq/day
- Can be increased to 6 mEq in 6h if having CNS event (Rule of 6’s)
- Give patient 100 cc bolus of 3% saline over 10-60 minutes
- Should raise Na by 2 mEq/L
- You may give a second 100 cc bolus if patient continues to seize
- DDAVP 1-2 mg (little evidence in humans)
- Avoid in psychogenic polydipsia
- D5W 6 cc/kg over an hour with meds (consult renal)
Assuming there is no neuro emergency, it is important to figure out the pt’s fluid status. Although it is difficult to estimate the pt volume status clinically at the bedside with any accuracy, we can look at the pt history (i.e. vomiting), HR, BP, JVD, presence of pedal edema, orthopedic VS and the point of care U/S of the IVC. This can be used to make rough determination of fluid status which dictates whether pt gets fluids, has fluid restriction and/or gets diuretics.
In the hypovolemic, hyponatremic pt, it is important to restore volume but be mindful of the sodium concentration of the fluid you use. Using Ringers lactate has a Na of 128 will likely result in slower rise serum sodium than using normal saline.
In the pt who is hypokalemic and hyponatremic, correcting the hypokalemia will help raise the sodium but may result in overcorrection of the sodium. It is important to correct hypokalemia as it is a risk factor for developing osmotic demyelination (AKA
central pontine myolysis) but it is important to factor in the contribution of supplemental K in raising Na. Other risk factors for developing OD are being elderly, malnourished state and chronic severe hyponatremia.
We talked about the Rule of 6’s in correcting Na (ie raise Na 6 points) in 6hrs if seizure or coma but raise Na 6 points in 24hrs if no neuro emergency. There is also the Rule of 100s to prevent rapid overcorrection. This rule is based on the fact that the rapid rise in Na is due to more to the pt’s free water diuresis after you give fluids than to the fluids that you are giving. Monitoring the urine output is key to preventing overcorrection of the Na. Therefore, in the pt with critically low Na, urine output and IVF need to be closely monitored:
-if urine output >100cc/hr, send STAT urine osmolariy and Na
-if urine osmolarity<100, consider DDAVP
-continue to follow latter 2 steps
In terms of causes of hyponatremia, meds such as SSRIs cause SIADH and hyponatremia and chronic steroids cause adrenal insufficiency. Exercise associated hyponatremia is seen amongst endurance athletes (i.e. marathon runners). Their hyponatremia results from taking in more free water than they are able to clear in their urine. One can blow the case by assuming that their change in MS or other complaints are due to dehydration rather than hyponatremia.
Pts taking ecstasy may become dehydrated and commonly (more in females) develop mild hyponatremia and occasionally severe hyponatremia. Short of not taking ecstasy, these pts should be encouraged to drink fluids with electrolytes. In the runner or pt who has taken ecstasy presenting with CNS event, consider empiric treatment of hyponatremia.
Tintinalli, Judith E., and J. Stephan. Stapczynski. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York: McGraw-Hill, 2011.
Sterns, Richard. “Overview of the treatment of hyponatremia in adults.” Up To Date. http://www.uptodate.com, 06 Apr. 2015. Web. 15 Feb. 2016. http://www.uptodate.com/contents/overview-of-the-treatment-of-hyponatremia-in-adults
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