Hyponatremia (Low Level of Sodium in the Blood) – Hormonal and Metabolic Disorders

By

James L. Lewis III

, MD, Brookwood Baptist Health and Saint Vincent’s Ascension Health, Birmingham

Reviewed/Revised Sep 2021 | Modified Sep 2022

VIEW PROFESSIONAL VERSION

In hyponatremia, the level of sodium in blood is too low.

• A low sodium level has many causes, including consumption of too many fluids, kidney failure, heart failure, cirrhosis, and use of diuretics.

• Symptoms result from brain dysfunction.

• At first, people become sluggish and confused, and if hyponatremia worsens, they may have muscle twitches and seizures and become progressively unresponsive.

• The diagnosis is based on blood tests to measure the sodium level.

• Restricting fluids and stopping use of diuretics can help, but severe hyponatremia is an emergency requiring use of drugs, intravenous fluids, or both.

(See also Overview of Electrolytes Overview of Electrolytes Well over half of the body’s weight is made up of water. Doctors think about the body’s water as being restricted to various spaces, called fluid compartments. The three main compartments are… read more and Overview of Sodium’s Role in the Body Overview of Sodium’s Role in the Body Sodium is one of the body’s electrolytes, which are minerals that the body needs in relatively large amounts. Electrolytes carry an electric charge when dissolved in body fluids such as blood… read more .)

Hyponatremia occurs when the body contains too little sodium Overview of Sodium’s Role in the Body Sodium is one of the body’s electrolytes, which are minerals that the body needs in relatively large amounts. Electrolytes carry an electric charge when dissolved in body fluids such as blood. .. read more for the amount of fluid it contains. The body may have too much, too little, or a normal amount of fluid. In all cases, however, sodium is diluted. For example, people with severe vomiting or diarrhea lose sodium. If they replace their fluid losses with just water, sodium is diluted.

Disorders, such as kidney disorders (for example, glomerulonephritis Glomerulonephritis Glomerulonephritis is a disorder of glomeruli (clusters of microscopic blood vessels in the kidneys with small pores through which blood is filtered). It is characterized by body tissue swelling… read more ) and other disorders (for example, cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver’s internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar… read more , and heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or. .. read more ), can cause the body to retain sodium and fluid. Often the body retains more fluid than sodium, which means the sodium is diluted.

Certain conditions may cause people to drink too much water (polydipsia), which can contribute to the development of hyponatremia.

Thiazide diuretics (sometimes called water pills) are a common cause of hyponatremia. These drugs increase sodium excretion, which increases water excretion. Thiazide diuretics are usually well-tolerated but can cause hyponatremia in people prone to low sodium, particularly the elderly.

Vasopressin (also called antidiuretic hormone) is a substance naturally produced in the body that helps regulate the amount of water in the body by controlling how much water is excreted by the kidneys. Vasopressin decreases water excretion by the kidneys, which retains more water in the body and dilutes the sodium. The pituitary gland produces and releases vasopressin when the blood volume (amount of fluid in the blood vessels) or blood pressure goes down or when levels of electrolytes (such as sodium) become too high.

Pain, stress, exercise, a low blood sugar level, and certain disorders of the heart, thyroid gland, kidneys, or adrenal glands can stimulate the release of vasopressin from the pituitary gland. The following are some of the drugs that stimulate the release of vasopressin or enhance its action at the kidney:

• Antipsychotic and antidepressant drugs

• Aspirin, ibuprofen, and many other nonprescription pain relievers (analgesics)

• Carbamazepine (an anticonvulsant)

• Chlorpropamide (which lowers the blood sugar level)

• Clofibrate (which lowers cholesterol levels)

• Ecstasy (3,4-methylenedioxymethamphetamine [MDMA])

• Oxytocin (used to induce labor)

• Vasopressin (synthetic antidiuretic hormone)

• Vincristine (a chemotherapy drug)

A frequent cause of hyponatremia is the syndrome of inappropriate secretion of antidiuretic hormone Syndrome of Inappropriate Secretion of Antidiuretic Hormone (SIADH) The syndrome of inappropriate secretion of antidiuretic hormone develops when too much antidiuretic hormone (vasopressin) is released by the pituitary gland under certain inappropriate conditions. .. read more (SIADH), in which vasopressin is inappropriately secreted in a variety of other situations (such as certain cancers, infections, and brain disorders).

Other causes of hyponatremia include

• Addison disease Adrenal Insufficiency In adrenal insufficiency, the adrenal glands do not produce enough adrenal hormones. Adrenal insufficiency may be caused by a disorder of the adrenal glands, a disorder of the pituitary gland… read more (underactive adrenal glands)

• Blockage of the small intestine

• Brain disorders such as head injury Overview of Head Injuries Head injuries that involve the brain are particularly concerning. Common causes of head injuries include falls, motor vehicle crashes, assaults, and mishaps during sports and recreational activities… read more , bleeding, stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that. .. read more , infections, or tumors

• Burns, if severe

• Cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver’s internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar… read more (formation of scar tissue in the liver)

• Consumption of too much water, as occurs in some mental disorders

• Diarrhea

• Drugs such as barbiturates, carbamazepine, chlorpropamide, clofibrate, diuretics (most common), opioids, tolbutamide, and vincristine

• Heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or… read more

• Hypothyroidism Hypothyroidism Hypothyroidism is underactivity of the thyroid gland that leads to inadequate production of thyroid hormones and a slowing of vital body functions. Facial expressions become dull, the voice… read more (underactive thyroid gland)

• Kidney disorders

• Pancreatitis Overview of Pancreatitis Pancreatitis is inflammation of the pancreas. The pancreas is a leaf-shaped organ about 5 inches (about 13 centimeters) long. It is surrounded by the lower edge of the stomach and the first… read more

• Peritonitis Peritonitis Abdominal pain is common and often minor. Severe abdominal pain that comes on quickly, however, almost always indicates a significant problem. The pain may be the only sign of the need for surgery… read more (inflammation of the abdominal cavity)

• Syndrome of inappropriate secretion of antidiuretic hormone Syndrome of Inappropriate Secretion of Antidiuretic Hormone (SIADH) The syndrome of inappropriate secretion of antidiuretic hormone develops when too much antidiuretic hormone (vasopressin) is released by the pituitary gland under certain inappropriate conditions. .. read more (SIADH)

• Vomiting

The brain is particularly sensitive to changes in the sodium level in blood. Therefore, symptoms of brain dysfunction, such as sluggishness (lethargy) and confusion, occur first. If the sodium level in blood falls quickly, symptoms tend to develop rapidly and be more severe. Older people are more likely to have severe symptoms.

As hyponatremia becomes more severe, muscle twitching and seizures may occur. People may become unresponsive, aroused only by vigorous stimulation (stupor), and eventually cannot be aroused (coma). Death may follow.

Hyponatremia is diagnosed by measuring the sodium level in blood. Determining the cause is more complex. Doctors consider the person’s circumstances, including other disorders present and drugs taken. Blood and urine tests are done to evaluate the amount of fluid in the body, the concentration of blood, and content of urine.

Mild hyponatremia can be treated by restricting fluid intake to less than 1 quart (about 1 liter) per day. If a diuretic or other drug is the cause, the dose is reduced or the drug is stopped. If the cause is a disorder, it is treated.

Occasionally, people are given a sodium solution intravenously, a diuretic to increase excretion of fluid, or both, usually slowly, over several days. These treatments can correct the sodium level.

Some people, especially those with the syndrome of inappropriate secretion of antidiuretic hormone Syndrome of Inappropriate Secretion of Antidiuretic Hormone (SIADH) The syndrome of inappropriate secretion of antidiuretic hormone develops when too much antidiuretic hormone (vasopressin) is released by the pituitary gland under certain inappropriate conditions… read more , need long-term treatment for hyponatremia. Fluid restriction alone is often not enough to prevent recurrence of hyponatremia. Salt tablets can be used in people with mild to moderate chronic hyponatremia. Depending on the cause of hyponatremia and the amount of fluid in the person’ body, several drugs are available for treatment.

Severe hyponatremia is an emergency. To treat it, doctors slowly increase the level of sodium in the blood with intravenous fluids and sometimes with a diuretic. Newer drugs, called vaptans, are sometimes needed. Increasing the sodium level too rapidly can result in severe and often permanent brain damage.

Generic Name	Select Brand Names
aspirin	Anacin Adult Low Strength, Aspergum, Aspir-Low, Aspirtab , Aspir-Trin , Bayer Advanced Aspirin, Bayer Aspirin, Bayer Aspirin Extra Strength, Bayer Aspirin Plus, Bayer Aspirin Regimen, Bayer Children’s Aspirin, Bayer Extra Strength, Bayer Extra Strength Plus, Bayer Genuine Aspirin, Bayer Low Dose Aspirin Regimen, Bayer Womens Aspirin , BeneHealth Aspirin, Bufferin, Bufferin Extra Strength, Bufferin Low Dose, DURLAZA, Easprin , Ecotrin, Ecotrin Low Strength, Genacote, Halfprin, MiniPrin, St. Joseph Adult Low Strength, St. Joseph Aspirin, VAZALORE, Zero Order Release Aspirin, ZORprin
ibuprofen	Advil, Advil Children’s, Advil Children’s Fever, Advil Infants’, Advil Junior Strength, Advil Migraine, Caldolor, Children’s Ibuprofen, ElixSure IB, Genpril , Ibren , IBU, Midol, Midol Cramps and Body Aches, Motrin, Motrin Children’s, Motrin IB, Motrin Infants’, Motrin Junior Strength, Motrin Migraine Pain, PediaCare Children’s Pain Reliever/Fever Reducer IB, PediaCare Infants’ Pain Reliever/Fever Reducer IB, Samson-8
carbamazepine	Carbatrol, Epitol , Equetro, Tegretol, Tegretol -XR
oxytocin	Pitocin
vasopressin	Pitressin, Vasostrict
vincristine	Oncovin, Vincasar PFS
tolbutamide	Orinase, Tol-Tab

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Low sodium levels (hyponatremia): Symptoms and causes

Sodium is an electrolyte that helps regulate levels of water and other substances in the body. Hyponatremia is when there are low sodium levels in the blood. It can lead to lethargy, confusion, fatigue, and other symptoms.

Hyponatremia is the most common electrolyte disorder — research suggests that approximately 1.7% of people in the United States have the condition. It is more prevalent among people with cancer.

It can result from underlying conditions, such as kidney failure, or other factors, including drinking too much water or taking certain medications.

As the condition worsens, individuals may experience symptoms, such as:

• vomiting
• muscle twitches
• seizures

The definition of a low sodium level is below 135 milliequivalents per liter (meq/l). Severe hyponatremia occurs when levels drop below 125 meq/l. Health issues arising from extremely low sodium levels may be fatal.

Mild hyponatremia may not cause symptoms, but when they occur, they can include:

• confusion
• sluggishness
• a headache
• fatigue and low energy
• nausea
• restlessness
• irritability

If hyponatremia symptoms worsen, it may cause significant illness, disability, or in extreme cases, death.

Acute hyponatremia may also lead to serious brain swelling that can cause permanent disability or death.

If the condition worsens, it can cause severe symptoms, particularly in older adults. Severe symptoms may include:

• vomiting
• muscle weakness, spasms, and twitching
• lethargy
• disorientation

Doctors also associate mild chronic hyponatremia with the following complications:

• attention deficit
• gait instability
• osteoporosis
• fractures

Without adequate treatment, people with hyponatremia can develop:

• rhabdomyolysis, where the skeletal muscle tissues die
• altered mental status
• seizures
• a coma

Other medical conditions and factors that can cause sodium levels to fall include:

• gastrointestinal fluid loss from diarrhea or vomiting
• pancreatitis
• small bowel obstruction
• certain medications, including diuretics or nonsteroidal anti-inflammatory drugs.
• renal causes, such as acute or chronic renal failure
• congestive heart failure
• syndrome of inappropriate antidiuretic hormone (SIADH), where the body makes too much antidiuretic hormone

Taking the recreational drug ecstasy or MDMA also increases the risk of severe hyponatremia in some cases. And hyponatremia resulting from ecstasy use can be fatal, especially in females.

Hormone disorders are another known cause. These include Addison’s disease, which reduces the body’s production of the hormones cortisol and aldosterone. Additionally, hypothyroidism, which doctors characterize by low levels of thyroid hormone, is another potential cause of hyponatremia.

Learn more about how drinking too much water can lower sodium levels.

Certain factors increase the risk of developing hyponatremia, including:

• older age
• having specific conditions, such as SIADH or kidney, heart, or liver disease
• taking certain diuretics, antidepressants, or pain medications
• taking ecstasy
• lifestyle factors, such as intense exercise, which may cause people to drink lots of water quickly

People at risk of hyponatremia or who develop symptoms should consult their doctor immediately, as they may need urgent medical treatment.

Individuals with symptoms, including vomiting, seizures, or loss of consciousness, require immediate attention. They should call an ambulance or go to the nearest emergency room.

To diagnose low sodium levels, a doctor will take a medical history, perform a physical examination, and order a blood test.

If the blood screening indicates low sodium levels, a healthcare professional will typically need to perform additional tests to determine the cause.

Treatment for hyponatremia involves restoring sodium levels and addressing what has caused them.

Restoring blood sodium levels

Those with mild-to-moderate hyponatremia due to lifestyle factors or medication could increase their sodium to usual levels by drinking less and adjusting or switching their medications.

Individuals with severe symptoms often require hospitalization and an intravenous sodium treatment to get their sodium levels back to usual. They may also require drugs to treat seizures or other hyponatremia symptoms.

Treating the underlying cause

Often, the cause of hyponatremia is an underlying condition, which will usually require specific treatment.

For example, if a person has liver disease, kidney disease, or heart disease, these can be potential causes of hyponatremia. These conditions may require treatment with medications or surgery.

People with a thyroid disorder can typically manage their symptoms and prevent hyponatremia and other complications with medications. They may also need to make certain lifestyle changes, such as avoiding smoking and reducing alcohol consumption.

SIADH usually requires ongoing treatment to prevent hyponatremia. Individuals with the condition may need to restrict their intake of fluids and take salt tablets and other medications.

To avoid low blood sodium levels, a person should:

• avoid drinking excessive amounts of water
• consume sports drinks during intense exercise
• avoid taking ecstasy
• seek treatment for medical conditions
• discuss medications with a doctor
• seek medical care if vomiting or diarrhea symptoms persist

The outlook for people with low sodium levels depends on the severity of the condition and the underlying cause.

Acute hyponatremia, which develops quickly, is more severe than chronic cases, which have a longer onset time. In severe cases, the condition can be fatal.

To improve their outlook, people should be aware of the symptoms of hyponatremia and seek prompt medical attention if they experience them. Those at risk of low sodium levels should be especially vigilant.

Sodium

Sodium

Sodium

Sodium

Sodium (Na ⁺ ) – the main extracellular cation, which is of fundamental importance for the normal functioning of muscles and the nervous system. Most of the sodium in the body (about 85%) is found in the blood and lymph. Its balance is maintained by two main regulatory mechanisms – the antidiuretic hormone (vasopressin) and the specific feeling of thirst. Of these two governing systems, thirst is the more important. Even with a lack of antidiuretic hormone, resulting in the inability of the body to retain water, thirst is sufficient to maintain a normal plasma sodium concentration. In addition, sodium content is partly controlled by a hormone called aldosterone, which is produced by the adrenal glands.

Sodium regulates the volume of extracellular fluid: an increase in its level leads to an increase in the volume of extracellular fluid due to the retention of water in the body, and a decrease – to a decrease in the volume of extracellular fluid due to water loss. Sodium enters the body through food and drink, and is subsequently excreted through urine, feces, and sweat.

Low sodium levels (hyponatremia) can cause symptoms such as fatigue, nausea and vomiting, headache, loss of appetite, confusion or disorientation, hallucinations, loss of consciousness, or coma. Hyponatremia can cause cell damage due to the retention of excessive amounts of water in them. This can be especially dangerous for brain neurons.

Abnormally high levels of sodium in the blood (hypernatremia) can lead to the following symptoms: thirst, fatigue, swelling of the extremities, weakness, insomnia, rapid heartbeat, coma. An excess of sodium in body fluids can also lead to high blood pressure.

Preparation of patients according to the general rules

Restrictions:

It is necessary to stop taking drugs that distort the result of the study in advance (in agreement with the attending physician)

Vehicle medium: vacutainer with/without anticoagulant with/without gel phase, volume 4 or 6 ml

Sample stability:

• 3 days at (+ 2) – (+ 8) ⁰ C;
• 1 month at (-20) ⁰ C;
• avoid repeated defrosting and freezing.

Method: ISE (ion selective electrode), potentiometry

Analyzer : Roche Cobas Integra 400plus

Test System: Roche Diagnostics COBAS Integra, Na ⁺

Reference values ​​(norm): 136. 0-145.0 mmol/l

The main indications for the appointment of the analysis:

• detection or control of electrolyte imbalance
• disorders accompanied by edema
• monitoring of diseases of the kidneys or adrenal glands
• diseases of the cardiovascular system
• disorders of consciousness, behavior, as well as signs of excessive excitability of the central nervous system

Interpretation of results

Elevated blood sodium (hypernatremia ) is most often a problem in the elderly, infants and bedridden patients.

Causes of hypernatremia include:

• insufficient water intake
• excessive consumption of water containing sodium salts
• excess salt or sodium bicarbonate in the diet
• increased fluid loss due to excessive sweating, diarrhoea, burns, or use of diuretics
• low level of the hormone vasopressin
• high level of the hormone – aldosterone
• kidney disease
• Cushing’s syndrome
• diabetes mellitus
• medications: ampicillin, betamethasone, sodium bicarbonate, doxorubicin, carbamazepine, cortisone, methyldopa, methyltestosterone, oral contraceptives, prednisolone, steroids, tetracycline, cefotaxime

Low sodium levels in the blood (hyponatremia) are most commonly a problem in older people.

Causes of hyponatremia include:

• diuretics, antidepressants, and some pain medications
• kidney disease
• liver diseases, including cirrhosis
• severe diarrhea or vomiting
• heart failure
• increased levels of certain hormones such as antidiuretic hormone or vasopressin
• drinking too much water
• insufficient urination
• the presence of ketones in the blood
• hypothyroidism or hypothyroidism
• Addison’s disease
• pregnancy
• medications: amphotericin, vasopressin, vincristine, gentamicin, isosorbide dinitrate, non-steroidal anti-inflammatory drugs, captopril, carbamazepine, clofibrate, methylprednisolone, miconazole, morphine, nifedipine, omeprazole, laxatives, triamterene, trimethoprim, chlorothiazide, furosemide, chlorpropamide, cyclophosphamide
• Falsely low sodium levels (pseudohyponatremia) can occur with very high levels of lipids or proteins in the blood. It can also occur in severe hyperglycemia, as when glucose levels are high, intracellular water leaks into the extracellular space

Hyponatremia – a directory of diseases – HealthInfo

Low sodium (hyponatremia) – sodium concentration in the blood is less than 136 mmol/l.