Hyponatremia – Diagnosis and Treatment
Cardiovascular, Hematological / Oncological, Metabolic / Endocrine
Hyponatremia is the most common electrolyte disorder in adults. 3-6% of patients presenting to the ED are hyponatremic.
- mild (135-125 mEq/L).
- severe (less than 125 mEq/L).
Mild hyponatremia is associated with an increase in mortality (30%) and admission rates (14%).
At-risk populations include patients with:
- Kidney disease,
- Congestive heart failure,
- Liver disease,
- Diuretics use,
- Excessive water intake (especially in context of physical activity)
- Low protein diet and high-water intake.
- Acute hyponatremia = hyponatremia occurring in <48hrs.
- If the acuity cannot be determined assume chronic.
- Severity of symptoms reflects both rapidity of change and sodium level.
- Mild to moderate: headache, nausea, vomiting, muscle cramps.
- Severe symptoms: seizure, coma, delirium, altered level of consciousness.
- Treatment based on patient’s volume status (eg. orthostatic hypotension assessment, moisture of mucus membranes, peripheral edema, JVP, POCUS of IVC diameter, and collapsibility).
- Lab investigations include electrolytes, glucose, creatinine/GFR, urea, urine osmolality, and urine sodium. LFT’s and BNP if clinically indicated.
Acute Symptomatic Hyponatremia
- Acute decrease does not allow time to adapt the osmolality leading to brain swelling and herniation. Therefore, any symptoms require close monitoring – can deteriorate rapidly.
- Treatment for moderate symptoms:
- Infusion of 3% hypertonic saline at a rate of 0.5-2 mL/kg/hr until symptoms resolve and or sodium is corrected 4-6mEq/L.
- Treatment for severe symptoms:
- 100-150 mL bolus of 3% hypertonic saline over 10-20 minutes. This can be repeated up to 2 times until symptoms resolve and or sodium is corrected 4-6mEq/L.
*Re-check sodium 1 hour following bolus and infusion initiation and sodium every 4 hours.
Chronic Symptomatic Hyponatremia
- Patient’s osmolality has had the time to adapt to long-term hyponatremia.
- Greater risk of cerebral edema and subsequent osmotic demyelination syndrome (central pontine myelinolysis).
- Treatment of moderate symptoms – 150 ml bolus 3% hypertonic saline.
- Treatment of severe symptoms – 150mL bolus of 3% hypertonic saline given over 10-20 minutes. This can be repeated 1 time until symptoms resolve and or sodium is corrected 4-6mEq/L.
- Re-check sodium 1 hour following bolus and infusion initiation and sodium every 4 hours.
Asymptomatic Hyponatremia (Acute or Chronic)
- Hypovolemic hyponatremia requires fluid resuscitation with normal saline or lactate ringer’s 0.5-1.0mL/kg/hr with the goal of the patient becoming euvolemic. The sodium should be monitored every 6-8hrs.
- Euvolemic hyponatremia mainstay of treatment is a fluid restriction, generally 1-1.5L per day of fluids.
- Hypervolemic hyponatremia also requires fluid restriction of no more than 0.8L per day. For patients with congestive heart failure, chronic kidney disease, nephrotic syndrome, and cirrhosis: loop diuretics and salt restriction can be considered.
- Admit based on their clinical status.
- Overcorrection = rise > 10mEq/L in the first 24hrs or 8mEq/L if the patient has chronic hyponatremia or sodium was initially <120mEq/L.
- 4-6mEq/L encompasses good clinical effect and appropriate safety margins.
- When overcorrection occurs:
- Discontinue treatment immediately.
- Consult nephrologist, endocrinologist.
- Consider desmopressin.
- 2-4 micrograms every 8 hours IV.
- Monitor sodium every hour.
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
Moderate evidence – various guidelines and reviews have similar diagnostic approach and management. However, the quality of reliable research is not high.
OTHER RELEVANT INFORMATION
Clinical practice guideline on diagnosis and treatment of hyponatraemia.
Spasovski G, Vanholder R, Allolio B, Annane D, Ball S, Bichet D, et al. (2014;171(1):X1-X.)
-European journal of endocrinology.
Hyponatremia in the Emergency Department.
Springer BL, Gabler M. (2016;37(2) ).
-Emergency medicine reports | AHCMedia
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by the BC Emergency Medicine Network and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. The BC Emergency Medicine Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. The BC Emergency Medicine Network also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Oct 29, 2021
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