Episode 93: Hyponatremia treatment.
Catherine and Dr. Saito discuss how to treat hyponatremia in an effective and safe way, especially when the hyponatremia is severe.
Introduction: What is sodium?
By Hector Arreaza, MD. Read by Alyssa Der Mugrdechian, MD; and Gina Cha, MD.
Sodium is a white metal that does not exist in nature in its free form. In its solid form, it’s so soft that you could cut it like butter with a knife. It is the sixth most common element in the earth’s crust. Even though sodium only makes up to 0.2% of our body weight, it plays a key role in nerve conduction, muscle contraction, and most importantly regulating water balance.
Today we will be talking about low sodium, known as hyponatremia. We will focus on how to treat hyponatremia and will mention some common causes and symptoms. We hope you can learn something from us today.
This is the Rio Bravo qWeek Podcast, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California. Our program is affiliated with UCLA, and it’s sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home. This podcast was created for educational purposes only. Visit your primary care physician for additional medical advice.
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Hyponatremia treatment.
By Catherine Nguyen, MS4, Ross University School of Medicine. Comments by Steven Saito, MD; and Hector Arreaza, MD.
DEFINITION: Serum sodium concentration <135 mEq/L.
CAUSES:
-Advanced renal impairment > impairment in free water excretion > hypoosmolality of serum
-Diuretics (thiazides first 1-2 weeks)
-SIADH (Syndrome of inappropriate ADH, I call it the syndrome of EXCESSIVE ADH to help me remember it), caused by common meds.
-Heart failure (low cardiac output) & cirrhosis (arterial vasodilation impairment) > decreased tissue perfusion (baroreceptors in carotid sinus senses reduction in pressure) > stimulus of ADH
-GI fluid loss (diarrhea, vomiting)
-CNS disturbances (stroke, hemorrhage, infections, psychosis, trauma) > increases ADH release
-Malignancies > ectopic production of ADH (small cell carcinoma)
-Drugs > SSRI, carbamazepine, cyclophosphamide
-Potomania > patient drinks large amounts of beer and decreased intake of foods (solids).
PRESENTATION:
-Asymptomatic
-Nausea & malaise earliest findings (125-130)
-Headache, lethargy, muscle cramps, confusion/AMS, and eventually seizures, coma, and respiratory arrest (115-120)
-Acute hyponatremia encephalopathy may be reversible, but permanent neurologic damage or death can occur.
TREATMENT:
Clinic: Chronic cases of hyponatremia may require spread-out treatment. Hyponatremia is never normal.
-Mild hyponatremia > concentration of 130 to 134 mEq/L: NO treatment with hypertonic saline. Rather, the initial approach includes general measures that are applicable to all hyponatremic patients (i.e., identify and discontinue drugs that could be contributing to hyponatremia; identify and, if possible, reverse the cause of hyponatremia; and limit further intake of water [e.g., fluid restriction, discontinue hypotonic intravenous infusions].
-Moderate hyponatremia > concentration of 120 to 129 mEq/L
ASYMPTOMATIC - 50 mL bolus of 3 percent saline (ie, hypertonic saline) to prevent the serum sodium from falling further.
SYMPTOMATIC – (call ICU) 100 mL bolus of 3 percent saline, followed, if symptoms persist, with up to two additional 100 mL doses (to a total dose of 300 mL); each bolus is infused over 10 minutes.
-Severe hyponatremia > concentration of <120 mEq/L (call ICU)
INITIATE intravenous 3 percent saline beginning at a rate of 15 to 30 mL/hour, administered via a peripheral vein.
ALTERNATIVE OPTION is to give 1 mL/kg (maximum, 100 mL) boluses of 3 percent saline intravenously every six hours, with dose modification as needed. Some patients may also require desmopressin (dDAVP) to prevent overly rapid correction.
Osmotic demyelination syndrome:
-Brain adaptations that reduce the risk of cerebral edema makes the brain vulnerable to injury if chronic hyponatremia is too rapidly corrected.
-Large cohort study has shown that correction by less than 5 mEq/L per day was not associated with neurologic complications.
-More common when Na is <120 mEq/L.
-Symptoms include dysarthria, dysphagia, paraparesis or quadriparesis, behavioral disturbances, movement disorders, seizures, lethargy, altered mental status, and even coma.
MONITORING:
-Monitor the patient for symptoms and remeasure the serum sodium concentration hourly to determine the need for additional therapy.
-Monitoring can be spaced out when the serum sodium has been raised by 4 to 6 mEq/L to every 12 hours until the serum sodium is 130 mEq/L or higher.
-The rate of correction of hyponatremia should be 6 to 12 mEq per L in the first 24 hours and 18 mEq per L or less in 48 hours.
-Fluid restriction — Restriction to 50 to 60 percent of daily fluid requirements. In general, fluid intake should be less than 800 mL/day.
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Conclusion: Now we conclude our episode number 93 “Hyponatremia treatment.” Remember to correct sodium appropriately, especially in case of severe hyponatremia. Use hypertonic saline in patients with acute hyponatremia with sodium below 129, especially if they are symptomatic. Sodium should be corrected at a rate of 6 to 12 milliequivalents per liter in 24 hours, or less than 18 milliequivalents per liter in 48 hours. If done at a higher rate, there is a risk of causing the osmotic demyelinating syndrome. Even without trying, every night you go to bed being a little wiser.
This week we thank Hector Arreaza, Catherine Nguyen, Steven Saito, Alyssa Der Mugrdechian and Gina Cha. Audio edition by Suraj Amrutia. Thanks for listening to Rio Bravo qWeek Podcast. If you have any feedback, contact us by email at RioBravoqWeek@clinicasierravista.org, or visit our website riobravofmrp.org/qweek. See you next week!
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References:
Sterns, Richard H, MD. Overview of the treatment of hyponatremia in adults, UpToDate, June 11, 2021, https://www.uptodate.com/contents/overview-of-the-treatment-of-hyponatremia-in-adults. Accessed on May 11, 2022.
Sterns, Richard H, MD. Manifestations of hyponatremia and hypernatremia in adults, UpToDate, January 10, 2022. https://www.uptodate.com/contents/manifestations-of-hyponatremia-and-hypernatremia-in-adults. Accessed on May 11, 2022.
Osmotic demyelination syndrome (ODS) and overly rapid correction of hyponatremia, UpToDate, March 14, 2022, https://www.uptodate.com/contents/osmotic-demyelination-syndrome-ods-and-overly-rapid-correction-of-hyponatremia. Accessed on May 11, 2022.
Goh KP. Management of hyponatremia. Am Fam Physician. 2004 May 15;69(10):2387-94. PMID: 15168958.
