Sodium

Each of the following posts is going to cover a specific electrolyte.  I will give you a little information about the electrolyte, signs and symptoms of imbalances, and how to treat it.  Let’s start off with sodium, the major electrolyte in the extracellular compartment, specifically intravascular.

Sodium is a cation (has a positive charge) and is associated with chloride (an anion, negative charge), therefore chloride levels change with the sodium levels.  Sodium works to regulate fluid volume and maintain blood osmolality.  It exchanges with potassium and attracts chloride, assists with acid-base balance, and promotes neuromuscular response through the Na+/K+ pump.  I’m not going to get into the details of these functions, but please feel free to look into them more on your own!  A big thing to remember with sodium is that cerebral cells (or brain cells) are very sensitive to sodium imbalances.  It’s important to watch for central nervous system changes when a patient is experiencing a sodium imbalance.

The normal range of sodium is 135-145 mEq/L.

The most common electrolyte disorder is hyponatremia, or low sodium levels (<135 mEq/L).  The signs and symptoms of this are hypervolemia, crackles in the lungs and difficulty breathing, high or low blood pressure, nausea, abdominal cramps, low urine specific gravity, and altered mental status (headache, confusion, combative behavior).  The causes of hyponatremia are gastrointestinal fluid loss, adrenal insufficiency, nasogastric irrigation with water, diuretics, and the syndrome of inappropriate antidiuretic hormone (SIADH).  Other causes may be excessive administration of IV D5W, excessive water intake, excessive beer intake, and a prolonged low sodium diet.  To treat hyponatremia, IV access should be established and the patient should be administered LR or NS.  The patient should be on strict intake and output measurements, weighed daily, placed on water restrictions, and consume sodium rich foods.  It is very important to monitor for confusion and seizures as these could mean the sodium levels are critically low.  Sodium levels are critical when they drop below 115 mEq/L.  Signs of this are seizures, twitching, and possibly coma.  If levels are this low, administer 3% NS and monitor carefully.

A high sodium level (>145 mEq/L) is known as hypernatremia.  This is very rare.  Signs and symptoms are hypovolemia, fever, orthostatic hypotension, polyuria (increased urination) leading into oliguria (decreased urination), muscle weakness, nausea/vomiting/anorexia, dry sticky membranes, and altered mental status (restlessness, irritability).  The causes are diarrhea, diuretics, excessive sweating, ingestion of large amounts of sodium, hypertonic tube feeding without water, inadequate water ingestion, and salt water near-drowning.  To treat hypernatremia administer hypotonic IV fluid (D5W, 0.25% or 0.45% NS).  Place the patient on dietary sodium restrictions, increase water intake, monitor labs, and maintain a safe environment.  Critical levels are greater than 155 mEq/L and can cause seizures or coma.

Changes in sodium levels cause fluid shifts, just as fluid shifts can cause changes in sodium levels.  This is why it is so important to monitor intake and output so carefully with these conditions.

How about just one question today?

What are the critical levels related to imbalances in sodium?

 

References

McCarthy, M. (2011). Electrolyte imbalances [PowerPoint Slides].

White, B. (2009). Clients with fluid imbalances. In Black, J. M., & Hawks, J. H. (Eds). Medical-surgical nursing. Clinical management for positive outcomes, (Vol 1., 8th Ed), (pp. 127-150). St. Louis, MO: Elsevier Inc.

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