What is Hypernatremia?
Sodium is the main salt found outside the body’s cells and plays a key part in controlling the amount of water in your body. Our bodies keep the right balance of salt and water by making our urine more concentrated, thanks to a hormone called antidiuretic hormone (ADH), and by making us feel thirsty so we drink more fluids. These natural defense mechanisms to prevent excessive salt levels in the body, known as hypernatremia, can be compromised in certain groups of people, those with a deficiency of the hormone vasopressin, or those whose kidneys do not respond correctly. The term hypernatremia refers to a situation where the concentration of sodium in the blood is more than 145 milliequivalents per liter.
What Causes Hypernatremia?
Hypernatremia happens when your body has too much salt (sodium) compared to water. This can be due to losing more water than salt from your body or from having too much salt in your diet. Having more salt than water in your body is the most common reason for hypernatremia. This often goes hand in hand with having lower than normal body fluid levels (hypovolemia).
Conditions that cause both salt and water loss can lead to hypernatremia, especially if more water is lost than salt. Some examples of these conditions include stomach flu, vomiting, long-term use of a certain type of stomach tube, burns, and excessive sweating. Sweating excessively can be from physical activity, fever, or being in a hot environment.
Hypernatremia can also be due to conditions that cause your kidneys to lose water and salt such as kidney disease, blockage in urine flow, or use of certain water pills (also known as diuretics). High blood sugar levels or use of a drug called mannitol can cause this type of water and salt loss.
Lastly, hypernatremia can occur in conditions that cause your body to lose more water like diabetes insipidus, a condition that prevents your body from conserving water. Central diabetes insipidus happens when there isn’t enough of a hormone called ADH.
Common triggers for central diabetes insipidus can be unknown, head injury, brain tumor, or diseases that impact the pituitary gland (which makes ADH), such as sarcoidosis or histiocytosis. Nephrogenic diabetes insipidus, on the other hand, happens when the kidneys don’t respond to ADH.
This type of diabetes insipidus can either be inherited through genes or be triggered by certain medications like lithium, foscarnet, and demeclocycline. In rare cases, hypernatremia can happen if there isn’t enough drinking water available, such as in cases of breastfeeding infants, cases of child or elder abuse, or in people who can’t feel that they’re thirsty.
Having too much salt in your body often happens due to medical treatment. This can accompany improper mixing of formula, intake of too much sodium bicarbonate, salt tablet poisoning, a condition called hyperaldosteronism (where the body makes too much of a hormone called aldosterone), or swallowing too much sea water.
Risk Factors and Frequency for Hypernatremia
Hypernatremia, which is a high sodium level in the blood, is mainly seen in infants and elderly people. There are several reasons why it commonly occurs in these groups:
- It can happen to infants who don’t get enough water, either from ineffective breastfeeding or from conditions like gastroenteritis.
- Premature infants are particularly at risk because they have a small body size and they rely completely on their caregivers to provide fluids.
- People with neurological impairments can also develop hypernatremia since they may not drink enough water due to an impaired thirst mechanism or a lack of available water.
- In a hospital setting, patients may become hypernatremic if they receive fluids that are too concentrated, especially if they can’t drink enough water on their own.
Signs and Symptoms of Hypernatremia
Hypernatremia, which is a higher than normal sodium level, often causes signs and symptoms related to dehydration or loss of body fluids. When the sodium level in blood is too high (greater than 160 milliequivalents per liter or meq/L), it can cause problems with the central nervous system. Symptoms tend to occur when there is a quick rise in sodium levels and can vary depending on the age group.
Infants and children may become irritable and agitated, which can lead to tiredness, excessive sleepiness, or even a coma. They may also have high-pitched cries. Adults with hypernatremia usually feel extremely thirsty. People with a condition called diabetes insipidus, which is associated with hypernatremia, often experience excessive urination (polyuria) and extreme thirst (polydipsia).
Other symptoms of hypernatremia can include changes to the skin which may feel doughy or velvety because of loss of water from inside the cells. If hypernatremia is caused by low blood volume (hypovolemia), individuals may also have low blood pressure when standing up (orthostatic hypotension) and a rapid heart rate (tachycardia). In some rare cases, muscle tone and reflexes can be unusually high, and there might be sudden, uncontrolled muscle jerks (myoclonus).
It’s important to remember when dealing with children that the seriousness of dehydration can be underestimated during hypernatremia due to a shift of water from inside the cell to the outside. This can make the child appear less dehydrated than they truly are. Hypernatremia is a common symptom of a conditions called Diabetes Insipidus, which is characterized by excessive thirst and urination.
- Irritability and agitation in infants and children
- Lethargy, excessive sleepiness, or coma
- High-pitched cries in infants
- Excessive thirst in adults
- Over-urination and extreme thirst in diabetes insipidus patients
- Doughy or velvety skin texture due to loss of water from inside the cells
- Low blood pressure when standing up and a rapid heartbeat in cases of low blood volume
- Unusually increased muscle tone, reflexes, and sudden jerks
Testing for Hypernatremia
Hypernatremia, or high salt levels in your blood, can typically be identified based on your health history and a physical examination. To further clarify the cause, whether it’s related to your kidneys or another part of your body, doctors will check your blood and urine. They will look at the volume of blood and urine, the concentration ability, and osmolality, which is essentially a measure of how many particles are in a solution.
In a condition called Diabetes Insipidus (DI), your urine may be excessively diluted, with normal urine volume and urine osmolality being less than the osmolality of your blood. If DI is suspected, a test where you’re asked to avoid drinking water may be done along with the administration of a medication called desmopressin. If central DI is the cause of the high salt levels, desmopressin will lead to an increase in urine osmolality. If it’s a type of DI involving your kidneys (nephrogenic), there will be no response to desmopressin.
On the other hand, if the cause is not related to the kidneys (extrarenal), your body will try to conserve fluids. There will be low urine volume, high concentration, and urine osmolality greater than the osmolality of your blood.
Treatment Options for Hypernatremia
Managing high levels of sodium in the blood, known as hypernatremia, involves identifying and treating the root cause and correcting the balance of fluids and salts in the body. The aim of treatment is bringing the sodium levels in the blood serum and the volume of blood in the body back to normal. It’s best to replace fluids orally or through a feeding tube, if possible.
For patients with severe dehydration or shock, the first step is rehydration with isotonic fluids, which have the same concentration of dissolved particles as blood. After that, water balance in the body can be corrected. It’s crucial to remember that fixing hypernatremia too quickly can cause swelling in the brain because water may enter the brain cells too fast. As such, the aim is to decrease blood sodium levels by no more than 12 meq (a unit of concentration) in 24 hours. Therefore, it is essential to monitor blood serum sodium closely every 2 to 4 hours during the acute phase of getting the sodium level back to normal.
If a patient experiences seizures during this correction phase, this could be a signal of brain swelling due to rapid changes in the concentration of particles in the body fluids. At that point, the administration of low-concentration fluids should be stopped. The estimated water balance should be restored gradually over 48 to 72 hours, with a slow decrease in serum sodium not exceeding 0.5 meq per hour.
The patient’s progress needs to be monitored attentively to ensure the correction rate, urinary output, and ongoing losses are all in check. In cases where there’s too much sodium in the body, the patient may need to consume large amounts of water, which could lead to overhydration. In such cases, loop diuretics may be used to increase urination and at times, peritoneal dialysis might be required to remove excess sodium from the body.
For older children and adults with central Diabetes Insipidus, a condition that causes extreme thirst and excessive urination, desmopressin may be necessary. This medication, available in intranasal and oral forms, helps the kidneys to absorb more water. However, note that water intoxication (overhydration) and low sodium levels are potential side effects with the use of desmopressin.
What else can Hypernatremia be?
Here are some medical conditions that might be relevant to consider:
- Cirrhosis (a liver disease)
- Central diabetes insipidus (a condition affecting kidneys ability to balance water in the body)
- Diarrhea
- Hypocalcemia (low calcium levels in the blood)
- Hyponatremia (low sodium levels in the blood)
- Nephrogenic diabetes insipidus (a kidney disorder causing an imbalance of water in the body)
- Thirst defect (a condition causing excessive thirst)
- Type 1 diabetes mellitus (a condition in which the body does not produce insulin)
Possible Complications When Diagnosed with Hypernatremia
The most dangerous outcome of having too much salt (hypernatremia) in your blood is bleeding in the areas around your brain due to broken veins and blood clot in the dural sinus. This can cause permanent brain damage or even death. Too quick correction of chronic hypernatremia can lead to brain swelling, seizures, and permanent brain damage.
Common Side Effects:
- Bleeding in the areas around the brain
- Broken veins
- Blood clot in the dural sinus
- Permanent brain damage
- Potential death
- Brain swelling
- Seizures
- Permanent brain damage due to too quick correction of chronic hypernatremia
