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Low or High Sodium Blood Test? Causes, Symptoms & Diseases

Written by Joe Cohen, BS | Last updated:
Jonathan Ritter
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Joe Cohen, BS | Last updated:

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Sodium is an essential element in the blood, which plays an important role in water-electrolyte balance, muscle, and nerve function. Keep reading to find out how blood sodium levels affect your health, and how you can increase or decrease them.

People go to their doctor to get their sodium levels tested as part of a standard panel. Almost always, the results are not scrutinized, even though we know that you can be healthier and live longer when your results lie within optimal ranges. When I used to go to doctors and tried to discuss my results, they had no clue what these meant from a health perspective. All they cared about was whether they could diagnose me with some disease. If I complained a lot, then they might just brush me off as depressed so they could give me a pill.

What is Sodium?

Sodium (Na+) is an essential element in the body that plays an important role in various functions. Blood sodium enables water to travel from blood vessels to cells and from cells to blood vessels. It is also responsible for the water absorbed or released from the kidneys [1].

Salt is the main source of blood sodium. Very high amounts of dietary sodium may lead to high blood pressure and other complications [2].

Sodium concentration is closely related to blood osmolality, which measures the body’s electrolyte-water balance and kidney function [3].

The human body tries to maintain sodium in normal levels (135 mEq/L to 145 mEq/L) [4].

If the sodium is too high, then the human body produces hormones (human atrial natriuretic peptide concentrations) that increase the sodium released through urine [5].

If the blood osmolality increases (when blood gets more concentrated), the antidiuretic hormone (ADH) is released and the feeling of thirst is triggered. Thirst increases water retention and causes sodium to return to normal levels [3].

The levels of sodium are affected by levels of water in the blood, which is determined by water consumption, urination, or water losses, such as sweating. Non-normal levels of blood sodium usually occur due to too little water intake, too much water loss, or problems with the antidiuretic hormone (ADH) [6].

Sodium Levels

Sodium levels are part of the complete metabolic panel.

Normal levels of blood sodium range from 135 mEq/L (130 mmol/L) to 145 mEq/L (145 mmol/L) [4].

People with sodium levels lower than 135 mEq/L suffer from hyponatremia, whereas people with sodium levels over 145 mEq/L suffer from hypernatremia [4].

Low Sodium Levels (Hyponatremia)

Hyponatremia results from the inability of the kidney to discharge water, or from excessive water consumption. Hyponatremia is defined as blood sodium levels under 135 mEq/L [7].

Hyponatremia is classified as mild (130 to 134 mmol/l), moderate (125 to 129 mmol/l) and severe (<125 mmol/l). Further, hyponatremic disorders are divided into euvolemic, hypervolemic, and hypovolemic [3, 8].

Euvolemic Hyponatremia

Euvolemic hyponatremia is the most common form of hyponatremia. Sodium is increased, but the body fluid volume is normal. The most common cause is the syndrome of inappropriate antidiuretic hormone secretion (SIADH) [3, 7].

Causes

  • Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) [7, 3, 9, 8, 10, 11, 12]
  • Drugs that cause SIADH, like carbamazepine, chlorpropamide, clofibrate
    cyclophosphamide, desmopressin (AVP receptor activator), ecstasy, interferon, mirtazapine, nicotine, omeprazole, oxytocin, phenothiazines, prostaglandin synthesis inhibitors, opiate derivatives, serotonin‐reuptake inhibitors, tricyclic antidepressants, venlafaxine, and vincristine [3, 9, 13, 11, 12]
  • Excessive beer consumption (beer potomania) [7, 3, 14, 15, 11, 12, 16]
  • Primary polydipsia (excessive thirst and water consumption due to faulty thirst mechanism) [7, 17, 18, 11]
  • Drugs, such as eplerenone and trimethoprim [19, 20, 19]
  • Low thyroid hormone levels (hypothyroidism) [7, 3, 11, 12]
  • Kidney insufficiency [7, 3, 12]
  • Endurance exercise [7, 21, 11]
  • Old age [8, 9, 10]

Symptoms

  • Seizures [7]
  • Confusion [7]
  • Dizziness [7]
  • Forgetfulness [7]
  • Deviation from normal walking (gait disturbance) [7]

Hypervolemic Hyponatremia

Hypervolemic hyponatremia is the most serious condition caused by low sodium levels and occurs mainly due to heart failure, liver failure, and kidney disorder [3, 7].

This condition occurs when the total body sodium levels are increased, but the total body water (intracellular and extracellular fluid) is also excessive because the kidney cannot discharge the excess water. This leads to hyponatremia and edema [3, 7].

Causes

  • Heart failure [3, 22, 9, 11, 12]
  • Liver failure (cirrhosis) [3, 11, 12]
  • Kidney damage (nephrotic syndrome) [3, 11, 12]

Symptoms

  • Edema [13]
  • A swollen vein in the neck (increased jugular venous pressure) [13]
  • Heart failure [13]
  • Excessive stomach fluid (ascites) [13]

Hypovolemic Hyponatremia

Hypovolemic hyponatremia occurs when there is an excessive loss of water and blood sodium through the kidney. One of the most common causes is diuretic‐induced hyponatremia, where there are high sodium levels in urine [3].

Causes

  • Use of diuretics (substances causing increased urine) [3, 7, 9, 11, 12]
  • Salt-wasting nephropathy [3, 11]
  • Cerebral salt wasting (CSW) [3, 7, 15, 12]
  • Mineralocorticoid deficiency/kidney insufficiency [3, 7, 11]
  • Renal tubular acidosis [3, 7, 11]
  • Diarrhea and vomiting [3, 11, 11, 12]
  • Pancreatitis [3]
  • Blood loss [3, 12]
  • Bowel obstruction, burns, and peritonitis [3, 7, 11]
  • Excessive alcohol consumption [15]
  • Old age [8, 9, 10, 12]

Symptoms

  • Decreased skin elasticity [7, 13]
  • Dry mucous membranes [7, 13]
  • Low blood pressure when standing up [7, 13]
  • Increased heart rate [7, 13]

Low Sodium Levels (Hyponatremia) Negatives

1) Increased Risk of Bone Fractures

Several studies performed on a total of 7,493 elderly patients showed that hyponatremia is associated with an increased risk of hip and other bone fractures [23, 24, 25, 26].

A study of 404 anorexic women also showed that hyponatremia is associated with lower bone mass [27].

2) Increased Risk of Death

A study showed that both hypernatremia and hyponatremia increased the mortality rates among 7,317 hip fracture patients [28].

Another observational study on 16,206 patients before their orthopedic surgery showed that both hypernatremia and hyponatremia increased the risk of death and the length of hospital stay [29].

3) Low Blood Pressure

A study of 3,824 adults showed that a decrease in blood sodium by 1 mmol/l can cause a decrease in systolic blood pressure by 1 mmHg [30].

Ways to Increase Blood Sodium

1) Saline Injections

Saline (sodium chloride) injections are the recommended treatment for acute and chronic hyponatremia. A saline injection acts as a fluid and refills electrolytes. A saline injection of 3% is indicated for acute and severe hyponatremia, whereas 0.9% saline is indicated for hypovolemic cases [7, 13, 8, 31, 12].

2) Replace Drugs Causing SIADH

Drugs that cause SIADH include: Carbamazepine, chlorpropamide, clofibrate
cyclophosphamide, desmopressin (AVP receptor activator), ecstasy, interferon, mirtazapine, nicotine, omeprazole, oxytocin, phenothiazines, prostaglandin synthesis inhibitors, opiate derivatives, serotonin‐reuptake inhibitors, tricyclic antidepressants, venlafaxine, and vincristine [3, 9, 13, 8, 31].

Patients with hyponatremia should also stop using thiazide diuretics [13, 3, 32, 8].

3) Fluid Restriction

For chronic, euvolemic, or hypervolemic hyponatremia, fluid restriction is the first-line recommended treatment [33].

Restriction of all fluids, including water, cause an increase in blood osmolality, which leads to electrolyte-water balance and normal blood sodium levels [7, 13, 31].

A pilot study showed that fluid restriction improved the quality of life in 24 patients with hyponatremia caused by heart failure [34].

4) Avoid Alcohol

Hyponatremia is common among chronic alcohol drinkers, and avoiding excessive consumption can help prevent it [15].

Drinking excessive alcohol can cause diarrhea and vomiting, which increases the release of sodium from the kidney. Moreover, excessive alcohol drinking can lead to excessive thirst and water consumption, resulting in hyponatremia [15].

Beer potomania (excessive beer drinking) can cause an imbalance in the electrolyte levels and very low levels of sodium in the blood, causing hyponatremia [35].

5) Avoid Excessive Sweating Due to Exercise or Sauna

During exercise, the body produces a great amount of heat as a result of muscle contraction. Then, the heat is transferred from the body to the skin in the form of water, which is known as the process of sweating. Although sweat helps the body to maintain a normal temperature, valuable electrolytes are lost [36].

Excessive sweating from intense workouts may increase the loss of sodium from the body, leading to hyponatremia [36, 37].

Sauna goers should also be cautious, as excessive sweating can increase sodium loss from the body, thus fluid consumption with every sauna visit is essential [38].

6) Vasopressin Receptor Antagonist (Vaptans)

Vaptans, such as tolvaptan, conivaptan, and satavaptan, cause water loss while increasing blood sodium levels. These drugs do not affect electrolytes and do not impair kidney function [7, 39, 8, 40].

A meta-analysis of 15 RCTs suggested that vaptans can be used to treat hypervolemic and euvolemic hyponatremia [41].

7) Increase Salt Consumption

Salt consumption is associated with blood sodium levels, and an increase in salt consumption causes an increase in blood sodium [42].

Several studies, including a DB-RCT, of 228 people with normal levels and high levels of blood pressure, showed that an increase in salt consumption can cause an increase in blood sodium levels [43].

High Sodium Levels (Hypernatremia)

Hypernatremia is defined as blood sodium levels over 145 mEq/L. Hypernatremia can result from dehydration or from faulty thirst mechanism [44].

Hence, the high-risk groups are infants, the elderly, hospitalized patients, and people suffering from mental illnesses. Hypernatremic disorders are divided into euvolemic, hypovolemic, and hypervolemic hypernatremia [45, 11].

Euvolemic Hypernatremia

Euvolemic hypernatremia occurs when the water balance is negative and the sodium balance is normal. It is commonly known as pure water loss [46, 47, 48].

Causes of pure water loss include kidney-related disorders, such as central and nephrogenic diabetes insipidus, and non-kidney causes, such as hypodipsia and fever [46, 47, 48].

Causes

  • Central diabetes insipidus (very low amount of ADH) [11, 6]
  • Fever [11, 6]
  • Heavy breathing (hyperventilation) [11, 6]
  • Very decreased thirst (hypodipsia) [11, 6]
  • Drugs (e.g., amphotericin, aminoglycosides, lithium, and phenytoin) [11]
  • Nephrogenic diabetes insipidus [11]
  • Sickle cell disease [11]
  • Brain tumors [11]
  • Old age [49, 45, 50]
  • Very young age (infancy) [45]

Symptoms

  • Muscle weakness [45, 6]
  • Restlessness [45, 6, 48]
  • Insomnia [45]
  • Sleepiness [45, 6]
  • Irritability [11, 48]
  • Nausea [11, 6]
  • Impaired mental status [11, 6]
  • Rapid and deep breathing (hyperpnea) [45]
  • Coma [45, 6]

Hypervolemic Hypernatremia

Hypervolemic hypernatremia is relatively rare. It occurs after an excessive sodium intake together with limited water consumption. It is most common among hospitalized patients, infants, and the elderly [46, 47, 48, 51, 52].

Causes

  • Sodium gain from medical reasons [11, 6, 51, 52]
  • Cushing’s syndrome (excess of cortisol) [11]
  • Hyperaldosteronism (excess of aldosterone) [11, 6]
  • Kidney failure [11]
  • Old age [49, 45, 50]
  • Very young age (infantry) [45]

Symptoms

  • Muscle weakness [45, 6]
  • Restlessness [45, 6]
  • Insomnia [45]
  • Sleepiness [45, 6]
  • Irritability [11]
  • Nausea [11, 6]
  • Impaired mental status [11, 6]
  • Rapid and deep breathing (hyperpnea) [45]
  • Coma [45, 6]

Hypovolemic Hypernatremia

Hypovolemic hypernatremia results from sodium loss together with an even greater water loss from the body (net water loss). Causes can be kidney related, such as osmotic diuresis and use of diuretics and non-kidney related, such as body fluid losses [46, 47, 48].

Causes

  • Body fluid loss (e.g., burns, sweating) [11, 6]
  • Use of diuretics [11, 6]
  • Vomiting and diarrhea [11, 6]
  • Heat injury [11]
  • Osmotic diuresis [11]
  • Kidney disease [6]
  • Old age [49, 45, 50]
  • Very young age (infancy) [45]

Symptoms

  • Muscle weakness [45, 6]
  • Restlessness [45, 6]
  • Insomnia [45]
  • Sleepiness [45, 6]
  • Irritability [11]
  • Nausea [11, 6]
  • Impaired mental status [11, 6]
  • Rapid and deep breathing (hyperpnea) [45]
  • Coma [45, 6]

High Sodium Levels (Hypernatremia) Negatives

1) Increased Risk of Death

A study showed that hypernatremia increased the mortality rates among 7,317 hip fracture patients [28].

Another observational study on 16,206 patients before their orthopedic surgery showed that both hypernatremias increased the risk of death and the length of hospital stay [29].

The speed of restoring the water and sodium balance is important, as it affects the brain fluid volume. If the correction of hypernatremia is too fast, it could result in brain edema. Brain edema could also lead to brain bleeding, brain damage, and even death [53, 45].

Further, the very fast or very slow speed of correction of hypernatremia increased the risk of death in 131 hospitalized patients [54].

2) High Blood Pressure

A study of 3,824 adults showed that an increase in blood sodium by 1 mmol/l can cause an increase in systolic blood pressure by 1 mmHg [30].

Ways to Decrease Blood Sodium

1) Fluid Administration

Hypernatremia results from inadequate water intake, excessive sodium intake, or excessive water loss. Therefore, the management of hypernatremia should involve treating the underlying cause and correcting the sodium levels in the body [11, 55].

The recommended fluid administration can be done orally, via a feeding tube or with injections. Only hypotonic fluids are allowed, such as water, 5% dextrose, and 0.2% saline (sodium chloride) [56, 47, 11].

2) Treat the Underlying Cause

Hypernatremia can be caused by various disorders, which can be identified through medical history, clinical exams, and laboratory tests. Treatment could involve treating vomiting, stopping the use of diuretics, or administration of desmopressin to treat diabetes insipidus [46, 48].

3) Decrease Salt Consumption

Salt consumption is associated with blood sodium levels, and an increase in salt consumption is shown to cause an increase in blood sodium [42].

Several studies found that people with normal levels and high levels of blood pressure showed that a decrease in salt consumption can cause a decrease in blood sodium levels [43].

An 8-week of 19 patients with high blood pressure showed that reduction of salt consumption led to lower blood sodium and lower systolic blood pressure [57].

Irregular Sodium Levels?

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About the Author

Joe Cohen, BS

Joe Cohen, BS

Joe Cohen won the genetic lottery of bad genes. As a kid, he suffered from inflammation, brain fog, fatigue, digestive problems, anxiety, depression, and other issues that were poorly understood in both conventional and alternative medicine.Frustrated by the lack of good information and tools, Joe decided to embark on a journey of self-experimentation and self-learning to improve his health--something that has since become known as “biohacking”. With thousands of experiments and pubmed articles under his belt, Joe founded SelfHacked, the resource that was missing when he needed it. SelfHacked now gets millions of monthly readers.Joe is a thriving entrepreneur, author and speaker. He is the CEO of SelfHacked, SelfDecode and LabTestAnalyzer.His mission is to help people gain access to the most up-to-date, unbiased, and science-based ways to optimize their health.
Joe has been studying health sciences for 17 years and has read over 30,000 PubMed articles. He's given consultations to over 1000 people who have sought his health advice. After completing the pre-med requirements at university, he founded SelfHacked because he wanted to make a big impact in improving global health. He's written hundreds of science posts, multiple books on improving health, and speaks at various health conferences. He's keen on building a brain-trust of top scientists who will improve the level of accuracy of health content on the web. He's also founded SelfDecode and LabTestAnalyzer, popular genetic and lab software tools to improve health.

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