Hypernatremia

Hypernatremia is too much sodium in the blood.  

HI-perNAtremia= HI Sodium (NA) (remember Sodium’s symbol in the periodic table is Na).

Sodium is responsible for muscle contraction, nerve impulses and the balancing of the amount of minerals and water in the body. As you can imagine, a high level of blood sodium can be catastrophic if not remedied.

Sodium ingestion causes fluid retention. This is the body’s attempt to dilute the amount of sodium in the bloodstream. This increase in fluid causes increased body weight and increased blood pressure as the body tries to move all of that fluid around.

The normal serum sodium concentration is 135-145 mEq/L and most of the body’s sodium is found in the interstitial space (the fluid outside of cells).

How does the body use sodium?

Sodium is an electrolyte used by the body for a multitude of functions.  

One of the main roles of sodium is to balance and distribute the water in our bodies, helping to control blood pressure.  

It also helps with the conduction of nerve impulses and muscle contraction. If you remember, potassium also plays a role in this. Sodium and potassium work hand in hand to make sure these functions work effectively.  

Sources of Sodium

The body does not make sodium on it’s own, so we are reliant of our food intake to consume the necessary sodium required by our body to do it’s job.  

Sodium rich foods include:

Canned foods such as meats, beans, pastas and soups

Cheeses

Food sauces (such as soy)

Frozen prepared meals

Any meal in which table salt is added

How the Body Regulates Sodium  

When sodium becomes too high, sensors in the heart, blood vessels, and kidneys detect the increased osmolality and use the kidneys to excrete extra potassium. Osmolality is the measurement of any solvent in plasma.

Risk Factors for Hyperkalemia

Hypernatremia can be caused by fluid loss or sodium excess.

Dehydration is a common cause of hyperkalemia related to fluid loss. Causes of dehydration can include:

• drinking too little fluids (very common in the elderly)
• Vomiting or diarrhea
• Diuretics
• Excessive sweating

Any time a person is dehydrated, they have less water in their system (obviously), therefore less in their plasma (plasma is 91-92% water, and plasma is what’s located in the extracellular fluid). This causes the serum osmolality of sodium to rise. Remember, osmolality is the measurement of any solvent in plasma.

Think of it like a bowl will pebbles it in. The pebbles will take up a lot more room in the bowl if it only has one cup of water compared to if it has 10 cups of water. The body is the same. 10mEq of sodium is gonna look like a lot more in a dehydrated person when compared to a well-hydrated person.

People with diabetes insipidus are at risk of dehydration because of excess urination, causing water loss. There are two types of diabetes insipidus:

Cranial diabetes insipidus- body does not produce enough antidiuretic hormone, meaning large amounts of fluid are lost in the urine

Nephrogenic diabetes insipidus- body produces adequate levels of antidiuretic hormone, but the kidneys do not respond to in in normal ways, leading to large amounts of fluid loss in urine

Hypernatremia caused by excess sodium can be caused by:

• High ingestion of sodium (can be caused in the hospital due to inappropriate fluid replacement or administration of sodium bicarbonate)
• Hyperaldosteronism (adrenal glands produce excess aldosterone, which leads to increased real reabsorption of sodium)
• Kidney disease

Clinical Manifestations of Hypernatremia

The most common sign of hypernatremia is excessive thirst. This is your body trying to increase the water is plasma, thereby diluting the sodium present.

Physical examination of the patient with hypernatremia will show muscle twitching or spasms. This is because sodium is vitally important to the working of muscles and nerves. Patients may also experience altered mental status or lethargy.

Patients with severe hypernatremia can experience neurological symptoms such as seizures and coma. High sodium may also cause brain cells to shrink, which leads to vascular rupture and permanent neurological damage.

Generally, hypernatremia is defined by the following scale:

146-149mEq/L= mild hypernatremia

150-169mEq/L= moderate hypernatremia

>170mEq/L= severe hypernatremia

The mortality rate of hypernatremia is high, greater than 50% is some studies. Older adults have an increased risk of death due to hypernatremia.

Treatment of Hypernatremia

It is important to identify the underlying cause of hypernatremia and correct it. Oral hydration can be accomplished in patients with mild hypernatremia without GI involvement.

Pt’s requiring IV fluids should receive D5W, which is 5% dextrose in water. Sodium Chloride (NaCl) should not be used as it could increase the hypernatremia. Pts with excess sodium should

When decreasing the serum sodium level, it should not be decreased by greater than 0.5mEq/L/hour or or 10-12mEq/L per day. Sodium loss at a rate faster than this can lead to cerebral edema and seizures.

Furosemide (Lasix)- loop diuretic that inhibits sodium reabsorption

Nursing Interventions for Hypernatremia

Every patient that presents to the ER with signs of symptoms of hypernatremia (nausea, vomiting, diarrhea, muscle twitching) should be placed on the cardiac monitor.

Expect an EKG, and possibly more than one. Electrolyte imbalances usually occur in at least pairs, and some electrolytes cause electrical changes in the heart.

Assess the patient’s medical history for aldosteronism, DI, and diuretic use.

Volume status is important for the patient with hypernatremia. Intake of oral fluids should be monitored, as patients with hypernatremia may have increased thirst. Urine output should also be assessed.

Prepare for the patient to be admitted to the intensive care unit for critically ill patients with hypernatremia. For patients with mild and moderate hypernatremia, the med-surg floor may be all that is needed.

Serum sodium levels should be drawn every 4 hours to monitor for a decrease in sodium that does not exceed 10-12mEq/L/day.

Patients should be educated about fluid intake (when appropriate), as well as monitoring the amount of sodium ingested.

Education of the patient is important. Patients who know what to look for will do a better job keeping their sodium levels in check.

If your interested in some of the things I use as an ER nurse, you can check them out here.

Interested in becoming an ER nurse? Might I suggest this.