Table of ContentsView AllTable of ContentsWhat Is Hyponatremia?What Causes Low Sodium Levels?Symptoms of Low SodiumDiagnosing HyponatremiaTreating Low Sodium
Table of ContentsView All
View All
Table of Contents
What Is Hyponatremia?
What Causes Low Sodium Levels?
Symptoms of Low Sodium
Diagnosing Hyponatremia
Treating Low Sodium
Hyponatremiais an electrolyte disorder in which your body experiences lowsodiumin the blood. Symptoms of hyponatremia include nausea, confusion, and weakness. In extreme cases, it can cause seizures, coma, and even death.
Overhydration anddehydrationcan cause hyponatremia, throwing off the balance of electrolytes. To treat hyponatremia, you must address underlying issues and restore sodium and water levels in the body.
This article explains the symptoms, causes, and treatments of hyponatremia. It also covers possible complications and ways to prevent the condition.
Sodium Blood Test: Low, Normal, and High Levels
Hyponatremia means there is too little of the electrolyte sodium in your blood. For your body to function correctly, it needs balanced electrolytes. The main electrolytes include:
Sodium is anessential electrolytewith several roles. It is involved in maintaining cells' homeostasis (internal balance), helps regulate fluid in the body, and impacts muscle function and nerve conduction.
A normal sodium level is between 135 and 145 milliequivalents per liter (mEq/L). Hyponatremia is a sodium level of less than 135 mEq/L.If blood sodium levels fall above or below this level, you may develop symptoms and require medical attention to restore your body’s sodium and electrolyte balance.
What Causes Low Sodium Levels?
Hypovolemic Hyponatremia
Hypovolemic hyponatremia occurs when the body loses too much water, with an even greater decrease in the sodium level. Usually, the fluid loss is from the kidneys (for example, the overuse ofdiuretics) or the digestive tract (such as severe or persistent vomiting or diarrhea).
Hypovolemic hyponatremia is common at endurance sporting events, affecting as many as 6% of endurance cyclists, 8% of marathon runners, 11% of Ironman competitors, and 67% of ultramarathon contestants.Hyponatremia can occur if athletes sweat too much (sweat contains water and sodium) anddon’t replenish fluids and electrolytes.
Primary adrenal insufficiency, known asAddison’s disease, is another cause of hypovolemic hyponatremia.
Euvolemic Hyponatremia
Euvolemic hyponatremia occurs when the total amount of water in the body is increased, but the sodium level remains normal. This may happen with athletes who engage in intense exercises, like a marathon or triathlon and drink too much water to correct their hydration. It is also seen in people who consumeexcess amounts of alcoholor use the drug ecstasy.
Malnutrition, severehypothyroidism, and a water-retaining condition calledsyndrome of inappropriate antidiuretic hormone secretion (SIADH)can also cause euvolemic hyponatremia. With SIADH, your body makes too much of a hormone called antidiuretic hormone (ADH), leading to water retention and, eventually, hyponatremia. It is the most common cause of hyponatremia.
There are several causes of SIADH, including:
If you have one of these health conditions or are on medications with SIADH as a side effect, your healthcare provider may already regularly track your electrolytes.
If your healthcare provider does not track your electrolytes, ask them what signs or symptoms indicate a need for a panel to examine them. For example, if your body is holding onto too much water, you may notice increased swelling or edema that warrants a call to your provider.
Hypervolemic Hyponatremia
Hypervolemic hyponatremia occurs when the body holds on to too much water relative to its sodium content. Medical conditions that may cause this type of hyponatremia include:
A hypervolemic state can also happen temporarily in individuals who are pregnant.
Pseudohyponatremia
If you have hyperglycemia, a corrected sodium calculation is necessary to assess your sodium levels properly.
The symptoms of hyponatremia depend on the rate and severity of the sodium drop. Many people with hyponatremia have no symptoms—instead, the electrolyte abnormality is found incidentally through a blood test drawn for other purposes.
Hyponatremia may cause a variety of potential symptoms including:
Signs of volume overload (too much water) can manifest withedema(swelling of the limbs) orascites(accumulation of fluids in the abdomen).
By contrast, people with hypovolemic hyponatremia will often have signs of dehydration from volume loss (including dry mouth, decreased skin elasticity, andorthostatic hypotension).
Serious Complications Related to Low Sodium
In severe cases where sodium levels drop below 120 mEq/L, seizure and coma may occur along with acute encephalitis (brain swelling), brain damage, and even death.
Another rare complication of severe hyponatremia isrhabdomylosis. Inrhabdomyolysis, muscles begin to break down. The components released during muscle breakdown can cause kidney injury. With proper intervention, the condition is treatable.
Causes and Symptoms of Dehydration
The diagnosis of hyponatremia involves a medical history, physical examination, and various laboratory tests.
Physical Examination
In addition to reviewing your symptoms and medical history, your healthcare provider will perform a physical exam to check for dehydration andedema. A simple, in-office neurological exam may also be performed.
Laboratory Tests
The sodium level can be measured within a simple blood test called a basic metabolic panel. In addition, your healthcare provider may order one or several of the following tests to make a diagnosis of hyponatremia:
Your healthcare provider may also order other tests to determine the underlying cause of hyponatremia. These tests may include athyroid-stimulating hormone (TSH) test, cortisol test, or adrenocorticotropic hormone (ACTH) stim test.
The treatment of hyponatremia is complex and varies based on the underlying cause and other factors, such as:
Other therapies may include:
It is essential to treat hyponatremia promptly and appropriately.
Summary
Hyponatremia is a common electrolyte condition that varies considerably in severity and etiology (cause). If you are an athlete or have a medical condition that puts you at risk of altered sodium levels, understand the signs and symptoms of hyponatremia and seek help as needed. Additionally, if you have a transient (short-term) condition, such as an acute stomach bug, consider replacing fluids with an electrolyte drink instead of plain water.
If you are at higher risk, your healthcare provider, dietician, or other medical professional is an appropriate resource for developing a proper treatment plan to prevent hyponatremia and other electrolyte imbalances.
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Braun MM, Barstow CH, Pyzocha NJ.Diagnosis and management of sodium disorders: hyponatremia and hypernatremia.Am Fam Physician. 2015 Mar;91(5):299-307.
Sahay M, Sahay R.Hyponatremia: A practical approach.Indian J Endocrinol Metab. 2014 Nov-Dec;18(6):760-71. doi:10.4103/2230-8210.141320
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