Sodium is an electrolyte that plays a vital role in maintaining the normal function of the body’s cells, tissues, and organs. It helps regulate the balance of fluids in the body, control blood pressure, and maintain normal muscle and nerve function. The normal range for sodium levels in the blood is 135-145 mEq/L.
Hyponatremia is diagnosed when the sodium level falls below 135 mEq/L. Various factors, including imbalances in water and electrolyte intake and excretion, certain medications, underlying medical conditions, and lifestyle factors, can cause it. Hyponatremia can range in severity from mild to severe, and if left untreated, it can lead to serious complications.
Epidemiology
The prevalence of hyponatremia varies depending on the population studied, and the criteria used to define hyponatremia. Hyponatremia is a common electrolyte disorder, occurring in 20-35% of hospitalized patients. It is more common in women than in men.
It is particularly prevalent in critical care and postoperative patients, older adults who may have multiple health conditions, multiple medications (polypharmacy), and limited access to food and fluids.
The mortality rate for hyponatremia varies depending on the severity of the condition and the underlying cause. Mild to moderate hyponatremia is not associated with a high mortality rate, but severe hyponatremia can be life-threatening.
Anatomy
Pathophysiology
The concentration of sodium and water in the body is regulated by the balance between water intake and excretion. The thirst mechanism, controlled by hypothalamic osmoreceptors, regulates water intake, and the hormone ADH, produced in the hypothalamus and stored in the pituitary gland, regulates water excretion.
Changes in the concentration of sodium and water can cause either an increase or decrease in ADH secretion, which in turn affects water reabsorption in the kidneys. Baroreceptors in the carotid sinus can also stimulate ADH secretion, but to a lesser extent than osmoreceptors. A decreased ineffective circulating volume, nausea, pain, stress, and certain drugs can trigger ADH secretion.
There are three mechanisms that can cause the kidneys to be unable to excrete water: high ADH activity, high aldosterone activity, and low cardiac output. High ADH activity can be caused by decreased effective arterial blood volume, SIADH (syndrome of inappropriate antidiuretic hormone secretion), or cortisol deficiency.
Decreased arterial blood volume can be caused by hypovolemia, decreased cardiac output, or vasodilation. Brain disorders, lung disorders, certain medications, or various conditions such as nausea and pain cause SIADH. Cortisol deficiency, caused by adrenal insufficiency, can also lead to high ADH activity.
Pseudohyponatremia is a laboratory error that can occur when certain substances in the blood interfere with the measurement of sodium levels. High levels of triglycerides, cholesterol, or proteins in the blood often cause it. Many clinical laboratories still use indirect ion-selective electrode technology to measure sodium levels, which can be affected by these substances.
Nonconductive irrigant solutions, which are used in certain medical procedures, can also cause pseudo-hyponatremia. These solutions contain mannitol, glycine, or sorbitol and are used in urological and gynecological procedures such as transurethral resection of the prostate.
Etiology
There are three main types of hyponatremias based on extracellular fluid volume: hypovolemic, euvolemic, and hypervolemic. Vasopressin, a hormone that helps regulate the concentration of sodium and water in the body, can be released in response to various physiological stimuli. Hypothyroidism and adrenal insufficiency can also lead to increased vasopressin release.
Causes of hypovolemic hyponatremia include loss of gastrointestinal fluid, third spacing of fluids, use of diuretics, osmotic diuresis, salt-wasting nephropathies, cerebral salt-wasting syndrome, and mineralocorticoid deficiency. These conditions lead to a decrease in total body water more significantly than in total body sodium.
Hypervolemic hyponatremia is caused by conditions that lead to an increase in total body water that is greater than the increase in total body sodium, such as renal or extrarenal conditions such as acute or chronic renal failure and congestive heart failure. Euvolemic hyponatremia is caused by nonosmotic, pathological vasopressin release in normal volume status.
It can be caused by certain medications that can cause hyponatremia, including vasopressin analogues, medications that stimulate vasopressin release or enhance its effects, medications that affect urinary dilution, and medications. Illicit drugs such as MDMA can also cause hyponatremia.
Genetics
Prognostic Factors
The prognosis for individuals with hyponatremia caused by reversible conditions, such as medication use or excess water intake, is generally good with proper treatment. However, hyponatremia caused by underlying chronic diseases, such as kidney disease or heart failure, may have a more guarded prognosis.
In general, mild to moderate hyponatremia is not associated with a high mortality rate and can be effectively treated with appropriate management. However, severe hyponatremia can be life-threatening and may require hospitalisation and aggressive treatment. If left untreated or untreated hyponatremia can lead to severe complications such as muscle breakdown, changes in mental status, seizures, and coma.
Rapid correction of chronic hyponatremia (a drop of more than 10-12 mEq/L of sodium in 24 hours) can also lead to osmotic demyelination syndrome or enhance its effects, medications that affect urinary dilution, and medications. Illicit drugs such as MDMA can also cause hyponatremia.
Clinical History
Clinical History
The symptoms of hyponatremia depend on the severity and duration of the condition. Patients with mild to moderate hyponatremia or a gradual decrease in sodium levels may have minimal symptoms. On the contrary patients with severe hyponatremia or a rapid drop in sodium levels may experience a wide range of symptoms.
These include anorexia, nausea and vomiting, fatigue, headache, muscle cramps, altered mental status, agitation, seizures, and coma. The severity of symptoms generally increases as the sodium concentration in the blood decreases.
Physical Examination
Physical Examination
In addition to evaluating symptoms, it is important to take a detailed medical history when diagnosing hyponatremia. This should include information about pulmonary or CNS disorders, medication history, and social history, such as increased beer intake or MDMA use.
A physical examination should include an assessment of volume status and neurological status. Patients with neurological symptoms and signs should be treated promptly to prevent permanent neurological damage.
Age group
Associated comorbidity
Associated activity
Acuity of presentation
Differential Diagnoses
Differential Diagnoses
Mannitol overdose
Hyperglycemia
Hyperproteinemia
Hyperlipidemia
SIADH
Hypothyroidism
Congestive heart failure
Psychogenic polydipsia
Adrenal crisis
Liver failure
Laboratory Studies
Imaging Studies
Procedures
Histologic Findings
Staging
Treatment Paradigm
Treatment options for hyponatremia include:
Administering isotonic fluids
Withdrawal of diuretics
Vasopressin receptor antagonists
Treating the underlying condition
Sodium Supplements
Using loop diuretics
Fluid restriction to less than 1 litre per day may also be recommended. In recent years, selective vasopressin 2 receptor antagonists have been used to treat hyponatremia. These medications increase the excretion of water in the kidneys without affecting sodium levels, thereby increasing serum sodium. They are used in patients with euvolemic and hypervolemic conditions (except in cases of liver failure) when other measures have not successfully corrected the cause of hyponatremia.
In patients with normovolemic hypotonic hyponatremia, fluid restriction alone may be sufficient treatment. However, some patients with malnourished SIADH may benefit from a high protein intake to increase the solute load for renal excretion, which can help remove excess free water.
Sodium is an electrolyte that plays a vital role in maintaining the normal function of the body’s cells, tissues, and organs. It helps regulate the balance of fluids in the body, control blood pressure, and maintain normal muscle and nerve function. The normal range for sodium levels in the blood is 135-145 mEq/L.
Hyponatremia is diagnosed when the sodium level falls below 135 mEq/L. Various factors, including imbalances in water and electrolyte intake and excretion, certain medications, underlying medical conditions, and lifestyle factors, can cause it. Hyponatremia can range in severity from mild to severe, and if left untreated, it can lead to serious complications.
The prevalence of hyponatremia varies depending on the population studied, and the criteria used to define hyponatremia. Hyponatremia is a common electrolyte disorder, occurring in 20-35% of hospitalized patients. It is more common in women than in men.
It is particularly prevalent in critical care and postoperative patients, older adults who may have multiple health conditions, multiple medications (polypharmacy), and limited access to food and fluids.
The mortality rate for hyponatremia varies depending on the severity of the condition and the underlying cause. Mild to moderate hyponatremia is not associated with a high mortality rate, but severe hyponatremia can be life-threatening.
The concentration of sodium and water in the body is regulated by the balance between water intake and excretion. The thirst mechanism, controlled by hypothalamic osmoreceptors, regulates water intake, and the hormone ADH, produced in the hypothalamus and stored in the pituitary gland, regulates water excretion.
Changes in the concentration of sodium and water can cause either an increase or decrease in ADH secretion, which in turn affects water reabsorption in the kidneys. Baroreceptors in the carotid sinus can also stimulate ADH secretion, but to a lesser extent than osmoreceptors. A decreased ineffective circulating volume, nausea, pain, stress, and certain drugs can trigger ADH secretion.
There are three mechanisms that can cause the kidneys to be unable to excrete water: high ADH activity, high aldosterone activity, and low cardiac output. High ADH activity can be caused by decreased effective arterial blood volume, SIADH (syndrome of inappropriate antidiuretic hormone secretion), or cortisol deficiency.
Decreased arterial blood volume can be caused by hypovolemia, decreased cardiac output, or vasodilation. Brain disorders, lung disorders, certain medications, or various conditions such as nausea and pain cause SIADH. Cortisol deficiency, caused by adrenal insufficiency, can also lead to high ADH activity.
Pseudohyponatremia is a laboratory error that can occur when certain substances in the blood interfere with the measurement of sodium levels. High levels of triglycerides, cholesterol, or proteins in the blood often cause it. Many clinical laboratories still use indirect ion-selective electrode technology to measure sodium levels, which can be affected by these substances.
Nonconductive irrigant solutions, which are used in certain medical procedures, can also cause pseudo-hyponatremia. These solutions contain mannitol, glycine, or sorbitol and are used in urological and gynecological procedures such as transurethral resection of the prostate.
There are three main types of hyponatremias based on extracellular fluid volume: hypovolemic, euvolemic, and hypervolemic. Vasopressin, a hormone that helps regulate the concentration of sodium and water in the body, can be released in response to various physiological stimuli. Hypothyroidism and adrenal insufficiency can also lead to increased vasopressin release.
Causes of hypovolemic hyponatremia include loss of gastrointestinal fluid, third spacing of fluids, use of diuretics, osmotic diuresis, salt-wasting nephropathies, cerebral salt-wasting syndrome, and mineralocorticoid deficiency. These conditions lead to a decrease in total body water more significantly than in total body sodium.
Hypervolemic hyponatremia is caused by conditions that lead to an increase in total body water that is greater than the increase in total body sodium, such as renal or extrarenal conditions such as acute or chronic renal failure and congestive heart failure. Euvolemic hyponatremia is caused by nonosmotic, pathological vasopressin release in normal volume status.
It can be caused by certain medications that can cause hyponatremia, including vasopressin analogues, medications that stimulate vasopressin release or enhance its effects, medications that affect urinary dilution, and medications. Illicit drugs such as MDMA can also cause hyponatremia.
The prognosis for individuals with hyponatremia caused by reversible conditions, such as medication use or excess water intake, is generally good with proper treatment. However, hyponatremia caused by underlying chronic diseases, such as kidney disease or heart failure, may have a more guarded prognosis.
In general, mild to moderate hyponatremia is not associated with a high mortality rate and can be effectively treated with appropriate management. However, severe hyponatremia can be life-threatening and may require hospitalisation and aggressive treatment. If left untreated or untreated hyponatremia can lead to severe complications such as muscle breakdown, changes in mental status, seizures, and coma.
Rapid correction of chronic hyponatremia (a drop of more than 10-12 mEq/L of sodium in 24 hours) can also lead to osmotic demyelination syndrome or enhance its effects, medications that affect urinary dilution, and medications. Illicit drugs such as MDMA can also cause hyponatremia.
Clinical History
The symptoms of hyponatremia depend on the severity and duration of the condition. Patients with mild to moderate hyponatremia or a gradual decrease in sodium levels may have minimal symptoms. On the contrary patients with severe hyponatremia or a rapid drop in sodium levels may experience a wide range of symptoms.
These include anorexia, nausea and vomiting, fatigue, headache, muscle cramps, altered mental status, agitation, seizures, and coma. The severity of symptoms generally increases as the sodium concentration in the blood decreases.
Physical Examination
In addition to evaluating symptoms, it is important to take a detailed medical history when diagnosing hyponatremia. This should include information about pulmonary or CNS disorders, medication history, and social history, such as increased beer intake or MDMA use.
A physical examination should include an assessment of volume status and neurological status. Patients with neurological symptoms and signs should be treated promptly to prevent permanent neurological damage.
Differential Diagnoses
Mannitol overdose
Hyperglycemia
Hyperproteinemia
Hyperlipidemia
SIADH
Hypothyroidism
Congestive heart failure
Psychogenic polydipsia
Adrenal crisis
Liver failure
Treatment options for hyponatremia include:
Administering isotonic fluids
Withdrawal of diuretics
Vasopressin receptor antagonists
Treating the underlying condition
Sodium Supplements
Using loop diuretics
Fluid restriction to less than 1 litre per day may also be recommended. In recent years, selective vasopressin 2 receptor antagonists have been used to treat hyponatremia. These medications increase the excretion of water in the kidneys without affecting sodium levels, thereby increasing serum sodium. They are used in patients with euvolemic and hypervolemic conditions (except in cases of liver failure) when other measures have not successfully corrected the cause of hyponatremia.
In patients with normovolemic hypotonic hyponatremia, fluid restriction alone may be sufficient treatment. However, some patients with malnourished SIADH may benefit from a high protein intake to increase the solute load for renal excretion, which can help remove excess free water.
Fluid retention is considered the first line of therapy
Consider as a second-line therapy for moderate to severe hyponatremia
Administer 0.25 to 0.5g/kg every day orally according to the SIAD European guidelines.
Dose range
90.9kg-Administer 22.7 to 45.4 g/day
81.8 kg-Administer 20.4 to40.9 g/day
72.7 kg-Administer 18.1 to 36.3 g/day
63.6 kg-Administer 15.9 to 31.8 g/day
54.5 kg-Administer 13.6 to 27.2 g/day
45.5 kg-Administer 11 to 22.75 g/day
https://www.ncbi.nlm.nih.gov/books/NBK470386/
medtigo
Hyponatremia
Updated :
August 23, 2023
Sodium is an electrolyte that plays a vital role in maintaining the normal function of the body’s cells, tissues, and organs. It helps regulate the balance of fluids in the body, control blood pressure, and maintain normal muscle and nerve function. The normal range for sodium levels in the blood is 135-145 mEq/L.
Hyponatremia is diagnosed when the sodium level falls below 135 mEq/L. Various factors, including imbalances in water and electrolyte intake and excretion, certain medications, underlying medical conditions, and lifestyle factors, can cause it. Hyponatremia can range in severity from mild to severe, and if left untreated, it can lead to serious complications.
The prevalence of hyponatremia varies depending on the population studied, and the criteria used to define hyponatremia. Hyponatremia is a common electrolyte disorder, occurring in 20-35% of hospitalized patients. It is more common in women than in men.
It is particularly prevalent in critical care and postoperative patients, older adults who may have multiple health conditions, multiple medications (polypharmacy), and limited access to food and fluids.
The mortality rate for hyponatremia varies depending on the severity of the condition and the underlying cause. Mild to moderate hyponatremia is not associated with a high mortality rate, but severe hyponatremia can be life-threatening.
The concentration of sodium and water in the body is regulated by the balance between water intake and excretion. The thirst mechanism, controlled by hypothalamic osmoreceptors, regulates water intake, and the hormone ADH, produced in the hypothalamus and stored in the pituitary gland, regulates water excretion.
Changes in the concentration of sodium and water can cause either an increase or decrease in ADH secretion, which in turn affects water reabsorption in the kidneys. Baroreceptors in the carotid sinus can also stimulate ADH secretion, but to a lesser extent than osmoreceptors. A decreased ineffective circulating volume, nausea, pain, stress, and certain drugs can trigger ADH secretion.
There are three mechanisms that can cause the kidneys to be unable to excrete water: high ADH activity, high aldosterone activity, and low cardiac output. High ADH activity can be caused by decreased effective arterial blood volume, SIADH (syndrome of inappropriate antidiuretic hormone secretion), or cortisol deficiency.
Decreased arterial blood volume can be caused by hypovolemia, decreased cardiac output, or vasodilation. Brain disorders, lung disorders, certain medications, or various conditions such as nausea and pain cause SIADH. Cortisol deficiency, caused by adrenal insufficiency, can also lead to high ADH activity.
Pseudohyponatremia is a laboratory error that can occur when certain substances in the blood interfere with the measurement of sodium levels. High levels of triglycerides, cholesterol, or proteins in the blood often cause it. Many clinical laboratories still use indirect ion-selective electrode technology to measure sodium levels, which can be affected by these substances.
Nonconductive irrigant solutions, which are used in certain medical procedures, can also cause pseudo-hyponatremia. These solutions contain mannitol, glycine, or sorbitol and are used in urological and gynecological procedures such as transurethral resection of the prostate.
There are three main types of hyponatremias based on extracellular fluid volume: hypovolemic, euvolemic, and hypervolemic. Vasopressin, a hormone that helps regulate the concentration of sodium and water in the body, can be released in response to various physiological stimuli. Hypothyroidism and adrenal insufficiency can also lead to increased vasopressin release.
Causes of hypovolemic hyponatremia include loss of gastrointestinal fluid, third spacing of fluids, use of diuretics, osmotic diuresis, salt-wasting nephropathies, cerebral salt-wasting syndrome, and mineralocorticoid deficiency. These conditions lead to a decrease in total body water more significantly than in total body sodium.
Hypervolemic hyponatremia is caused by conditions that lead to an increase in total body water that is greater than the increase in total body sodium, such as renal or extrarenal conditions such as acute or chronic renal failure and congestive heart failure. Euvolemic hyponatremia is caused by nonosmotic, pathological vasopressin release in normal volume status.
It can be caused by certain medications that can cause hyponatremia, including vasopressin analogues, medications that stimulate vasopressin release or enhance its effects, medications that affect urinary dilution, and medications. Illicit drugs such as MDMA can also cause hyponatremia.
The prognosis for individuals with hyponatremia caused by reversible conditions, such as medication use or excess water intake, is generally good with proper treatment. However, hyponatremia caused by underlying chronic diseases, such as kidney disease or heart failure, may have a more guarded prognosis.
In general, mild to moderate hyponatremia is not associated with a high mortality rate and can be effectively treated with appropriate management. However, severe hyponatremia can be life-threatening and may require hospitalisation and aggressive treatment. If left untreated or untreated hyponatremia can lead to severe complications such as muscle breakdown, changes in mental status, seizures, and coma.
Rapid correction of chronic hyponatremia (a drop of more than 10-12 mEq/L of sodium in 24 hours) can also lead to osmotic demyelination syndrome or enhance its effects, medications that affect urinary dilution, and medications. Illicit drugs such as MDMA can also cause hyponatremia.
Clinical History
The symptoms of hyponatremia depend on the severity and duration of the condition. Patients with mild to moderate hyponatremia or a gradual decrease in sodium levels may have minimal symptoms. On the contrary patients with severe hyponatremia or a rapid drop in sodium levels may experience a wide range of symptoms.
These include anorexia, nausea and vomiting, fatigue, headache, muscle cramps, altered mental status, agitation, seizures, and coma. The severity of symptoms generally increases as the sodium concentration in the blood decreases.
Physical Examination
In addition to evaluating symptoms, it is important to take a detailed medical history when diagnosing hyponatremia. This should include information about pulmonary or CNS disorders, medication history, and social history, such as increased beer intake or MDMA use.
A physical examination should include an assessment of volume status and neurological status. Patients with neurological symptoms and signs should be treated promptly to prevent permanent neurological damage.
Differential Diagnoses
Mannitol overdose
Hyperglycemia
Hyperproteinemia
Hyperlipidemia
SIADH
Hypothyroidism
Congestive heart failure
Psychogenic polydipsia
Adrenal crisis
Liver failure
Treatment options for hyponatremia include:
Administering isotonic fluids
Withdrawal of diuretics
Vasopressin receptor antagonists
Treating the underlying condition
Sodium Supplements
Using loop diuretics
Fluid restriction to less than 1 litre per day may also be recommended. In recent years, selective vasopressin 2 receptor antagonists have been used to treat hyponatremia. These medications increase the excretion of water in the kidneys without affecting sodium levels, thereby increasing serum sodium. They are used in patients with euvolemic and hypervolemic conditions (except in cases of liver failure) when other measures have not successfully corrected the cause of hyponatremia.
In patients with normovolemic hypotonic hyponatremia, fluid restriction alone may be sufficient treatment. However, some patients with malnourished SIADH may benefit from a high protein intake to increase the solute load for renal excretion, which can help remove excess free water.
https://www.ncbi.nlm.nih.gov/books/NBK470386/
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