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Saturday, January 17, 2015

Clinical Manifestations of Hyponatremia

Sodium deficiency, hyponatremia, nurse, electrolyte

In this post on hyponatremia I'll discuss the pathophysiology, what causes it, the clinical manifestations, and how to treat the imbalance. 
Since you are looking at HYPOnatremia, you might want to check my post on HYPERnatremia as well.


Hyponatremia means low levels of sodium. We know that normal levels of sodium range from 135 to 145 mEq/L. If you did not know that, then I suggest reading my post on Lab Values Every Nurse Needs to Know. (It has a table you can print off and carry with you. I keep one on my badge.)

Hyponatremia can range from mild to severe. In severe cases of low sodium it can cause major neurological damage and death. In hyponatremia the cell {SWELLS} as H2O is pulled into the cell. 

(The opposite happens in HYPERnatremia. The cell {shrinks} as H2O is pulled out of the cell because of the excess sodium.)

Let's get back to HYPOnatremia... 

Causes of Hyponatremia

Loss of Sodium
  • Use of diuretics
  • Loss of GI fluids
  • Adrenal insufficiency
  • Osmotic diuresis
  • Salt-losing nephritis
Gains of Water
  • Excessive administration of D5W or other hypotonic fluids
  • Psychogenic polydipsia (because antipsychotic drugs cause dry mouth)
  • Excessive water administration with tube feedings
  • Excessive water intake during exercise
  • Thiazide diuretics
  • Tricyclic antidepressants
  • SSRIs
  • Antineoplastic agents
  • Carbamazepine
  • Oxytocin
  • Desmopressin acetate
  • Chlorpropamide
  • Ecstasy

Ok. That's a lot to digest. But just think, what's going to throw that balance off? Either I'm losing sodium or I'm diluting the sodium in my body by increasing fluids. I hope that helps. 

Carbamazepine- prescribed as an anticonvulsant, causes ADH release. The release of ADH causes water retention, which then dilutes the sodium in our blood.

Oxytocin- Pay attention if you want to work in LABOR and DELIVERY!!! Oxytocin possess significant antidiuretic properties. When you give oxytocin in dextrose and water to stimulate labor, it results in water retention, thus leading to hyponatremia. This can lead to SEIZURES in mother and baby!

Clinical Manifestations of Hyponatremia

Refer to my beautiful artwork above or:
  • Nausea and Vomiting
  • Abdominal cramping
  • Lethargy
  • Headache
  • Seizures
  • Respiratory arrest
  • Coma

Treatment of Hyponatremia

We want to raise the level of sodium in the blood SAFELY and we want to treat the underlying cause.

This can be achieved by:
  • Sodium replacement if caused by sodium loss
  • Water restriction if caused by water overload
  • Hypertonic saline and furosemide (diuretic) if hyponatremia is causing neurological symptoms

If hyponatremia is treated too aggressively, raising levels more than 12 mEq/L in a 24-hour period, it can cause Central Pontine Myelinolysis. CPM is a condition that results from the shrinkage of neurons away from their myelin sheaths due to water shifts associated with too rapid of correction of hyponatremia.

Here's the link again to my post on the Clinical Manifestations of Hypernatremia. (See, I'm so nice. Now you don't have to scroll back up to the top of the page, or reload the homepage. Yay!)

You might also be interested in:
Everything You Need to Know About IV Fluids

If you have a question or want me to post about something specifically, leave a comment!



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