Electrolytes na. Electrolyte Panel: Essential Guide to Understanding Your Body’s Ionic Balance
What are electrolytes and why are they crucial for our health. How do sodium, potassium, calcium, and other key electrolytes function in the body. What happens when electrolyte levels become imbalanced. How is an electrolyte panel used to diagnose and monitor various medical conditions.
The Vital Role of Electrolytes in Human Physiology
Electrolytes are minerals dissolved in our body fluids that carry an electric charge. These ionized particles play a crucial role in maintaining various bodily functions, including nerve signaling, muscle contraction, and fluid balance. The most significant electrolytes in our body include sodium, potassium, chloride, magnesium, calcium, phosphate, and bicarbonate.
How do electrolytes impact our daily life? These charged particles are responsible for:
- Maintaining electrical neutrality in cells
- Generating and conducting action potentials in nerves and muscles
- Regulating fluid balance between intracellular and extracellular compartments
- Facilitating numerous enzymatic reactions
Where do we get electrolytes from? Our diet is the primary source of these essential minerals. The foods and beverages we consume provide the necessary electrolytes to maintain optimal bodily functions.
Sodium: The Extracellular Fluid Regulator
Sodium is a predominant cation in the extracellular fluid, playing a vital role in maintaining fluid balance and cellular function. How does sodium contribute to our body’s homeostasis?
- Regulates extracellular fluid volume
- Maintains cell membrane potential
- Facilitates active transport across cell membranes
The kidneys are primarily responsible for sodium regulation. Most sodium reabsorption occurs in the proximal tubule, with fine-tuning in the distal convoluted tubule. Aldosterone, a hormone produced by the adrenal glands, controls sodium transport via sodium-chloride symporters.
Sodium Imbalances: Hyponatremia and Hypernatremia
Hyponatremia, characterized by serum sodium levels below 135 mmol/L, is the most common electrolyte disorder. What are the symptoms of hyponatremia? Patients may experience:
- Headaches
- Confusion
- Nausea
- Delirium
Conversely, hypernatremia occurs when serum sodium levels exceed 145 mmol/L. Symptoms of hypernatremia include tachypnea, sleeping difficulty, and restlessness. It’s crucial to note that rapid sodium corrections can lead to severe complications such as cerebral edema and osmotic demyelination syndrome (ODS).
Potassium: The Intracellular Ion Powerhouse
Potassium is primarily an intracellular ion, playing a crucial role in maintaining cellular function and electrical gradients. How is potassium regulated in our body? The sodium-potassium adenosine triphosphatase (Na+/K+-ATPase) pump is the primary mechanism for maintaining potassium homeostasis. This pump actively transports sodium out of cells while bringing potassium in, creating an electrochemical gradient across cell membranes.
In the kidneys, potassium undergoes a complex process of filtration, reabsorption, and secretion:
- Filtration occurs at the glomerulus
- Reabsorption takes place in the proximal convoluted tubule and thick ascending loop of Henle
- Secretion happens in the distal convoluted tubule, influenced by aldosterone
Potassium Imbalances: Hypokalemia and Hyperkalemia
Hypokalemia is diagnosed when serum potassium levels fall below 3.6 mmol/L. What are the common symptoms of hypokalemia?
- Weakness
- Fatigue
- Muscle twitching
In severe cases, hypokalemic paralysis can occur, leading to generalized body weakness. This condition can be either familial or sporadic.
Hyperkalemia, on the other hand, is characterized by serum potassium levels above 5.5 mmol/L. This condition can result in serious cardiac arrhythmias. Additional symptoms may include:
- Muscle cramps
- Muscle weakness
- Rhabdomyolysis
- Myoglobinuria
Calcium: The Multifunctional Mineral
Calcium plays a diverse and crucial role in human physiology. What are the primary functions of calcium in our body?
- Skeletal mineralization
- Muscle contraction
- Nerve impulse transmission
- Blood clotting
- Hormone secretion
How is calcium regulated in our body? Several hormones work in concert to maintain calcium homeostasis:
- Vitamin D (1,25-dihydroxy vitamin D3): Controls calcium absorption in the intestine
- Parathyroid hormone (PTH): Regulates calcium secretion in the distal tubule of the kidneys
- Calcitonin: Acts on bone cells to increase blood calcium levels
Calcium Imbalances: Hypocalcemia and Hypercalcemia
Hypocalcemia is diagnosed when corrected serum total calcium levels fall below 8.8 mg/dL. This condition can result from vitamin D deficiency or hypoparathyroidism. It’s important to note that serum calcium levels should be routinely checked in post-thyroidectomy patients.
Hypercalcemia occurs when corrected serum total calcium levels exceed 10.7 mg/dL. What are the common causes of hypercalcemia?
- Primary hyperparathyroidism
- Malignancy-associated hypercalcemia (often due to PTHrP secretion)
Bicarbonate: The Body’s pH Buffer
Bicarbonate plays a crucial role in maintaining the acid-base balance in our body. How does bicarbonate contribute to pH regulation? The kidneys are primarily responsible for regulating bicarbonate concentration through two main mechanisms:
- Reabsorption of filtered bicarbonate
- Generation of new bicarbonate through net acid excretion (via titrable acid and ammonia excretion)
What can disrupt bicarbonate balance? Diarrhea is a common cause of bicarbonate loss, leading to acid-base imbalances. Additionally, various kidney disorders can result in excessive bicarbonate retention, potentially causing metabolic alkalosis.
Magnesium: The Overlooked Electrolyte
Magnesium is an often-overlooked electrolyte that plays a vital role in numerous physiological processes. What are the key functions of magnesium in our body?
- Enzyme cofactor in over 300 biochemical reactions
- Regulation of muscle and nerve function
- Energy production
- Protein synthesis
- Blood pressure regulation
How is magnesium regulated in our body? The kidneys play a crucial role in magnesium homeostasis, with the majority of filtered magnesium being reabsorbed in the thick ascending limb of the loop of Henle. Hormones such as parathyroid hormone and vitamin D also influence magnesium balance.
Magnesium Imbalances: Hypomagnesemia and Hypermagnesemia
Hypomagnesemia occurs when serum magnesium levels fall below 1.8 mg/dL. What are the common symptoms of hypomagnesemia?
- Muscle weakness
- Tremors
- Tetany
- Cardiac arrhythmias
Hypermagnesemia, while less common, can occur in patients with kidney dysfunction or excessive magnesium intake. Symptoms may include:
- Lethargy
- Confusion
- Respiratory depression
- Cardiac conduction abnormalities
The Importance of Electrolyte Panel Testing
An electrolyte panel is a blood test that measures the levels of key electrolytes in the body. Why is this test important? It helps healthcare providers:
- Diagnose electrolyte imbalances
- Monitor treatment effectiveness for various conditions
- Assess overall health and hydration status
When might a healthcare provider order an electrolyte panel? Common scenarios include:
- Evaluating symptoms of dehydration or overhydration
- Monitoring patients with kidney disease, heart failure, or liver disease
- Assessing the effects of certain medications on electrolyte balance
- Investigating unexplained fatigue, weakness, or confusion
Understanding the results of an electrolyte panel can provide valuable insights into a patient’s overall health and help guide treatment decisions.
Maintaining Electrolyte Balance: Diet and Lifestyle Factors
Maintaining proper electrolyte balance is crucial for optimal health and bodily function. How can we ensure adequate electrolyte levels through diet and lifestyle choices?
- Consume a balanced diet rich in fruits, vegetables, and whole grains
- Stay properly hydrated, especially during physical activity or in hot weather
- Replenish electrolytes lost through sweat during intense exercise
- Be mindful of excessive alcohol consumption, which can lead to electrolyte imbalances
- Monitor salt intake, especially for those with hypertension or heart conditions
Are there specific foods that are particularly rich in electrolytes? Some excellent sources include:
- Bananas and avocados (potassium)
- Leafy greens (magnesium and calcium)
- Nuts and seeds (various electrolytes)
- Dairy products (calcium)
- Fish (sodium and potassium)
By incorporating these foods into a balanced diet and maintaining healthy lifestyle habits, individuals can help support proper electrolyte balance and overall health.
Electrolyte Imbalances in Special Populations
Certain populations may be at higher risk for electrolyte imbalances due to various factors. Who are these special populations, and what unique considerations should be taken into account?
Athletes and Endurance Sports Participants
Athletes, particularly those engaged in endurance sports, are at risk for electrolyte imbalances due to excessive sweating. How can athletes maintain proper electrolyte balance?
- Proper hydration before, during, and after exercise
- Consumption of electrolyte-rich sports drinks during prolonged activity
- Regular monitoring of electrolyte levels, especially in extreme conditions
Elderly Individuals
Older adults may be more susceptible to electrolyte imbalances due to various factors. What are the key considerations for maintaining electrolyte balance in the elderly?
- Age-related changes in kidney function
- Potential medication interactions affecting electrolyte balance
- Decreased thirst sensation leading to inadequate fluid intake
- Chronic health conditions that may impact electrolyte regulation
Patients with Chronic Diseases
Individuals with certain chronic conditions may require special attention to their electrolyte balance. Which conditions are particularly associated with electrolyte disturbances?
- Chronic kidney disease
- Heart failure
- Liver cirrhosis
- Diabetes mellitus
- Adrenal gland disorders
For these patients, regular monitoring of electrolyte levels and close collaboration with healthcare providers is essential to maintain optimal health and prevent complications.
Emerging Research and Future Directions in Electrolyte Management
The field of electrolyte management is constantly evolving, with new research shedding light on the complex interplay between electrolytes and various physiological processes. What are some of the emerging areas of research in electrolyte management?
- Personalized electrolyte replacement strategies based on genetic profiles
- Novel biomarkers for early detection of electrolyte imbalances
- The role of electrolytes in neurodegenerative disorders
- Electrolyte balance in space travel and long-term microgravity exposure
- Advanced wearable technologies for real-time electrolyte monitoring
How might these advancements impact clinical practice in the future? As our understanding of electrolyte physiology deepens, we can expect:
- More targeted and efficient treatment strategies for electrolyte imbalances
- Improved prevention of electrolyte-related complications in various medical conditions
- Enhanced performance optimization for athletes through personalized electrolyte management
- Better management of electrolyte disorders in challenging environments, such as space exploration
As research in this field progresses, healthcare providers and patients alike will benefit from more sophisticated tools and knowledge to maintain optimal electrolyte balance and overall health.
Electrolytes – StatPearls – NCBI Bookshelf
Introduction
Electrolytes are essential for basic life functioning, such as maintaining electrical neutrality in cells and generating and conducting action potentials in the nerves and muscles. Significant electrolytes include sodium, potassium, chloride, magnesium, calcium, phosphate, and bicarbonates. Electrolytes come from our food and fluids.
These electrolytes can be imbalanced, leading to high or low levels. High or low levels of electrolytes disrupt normal bodily functions and can lead to life-threatening complications. This article reviews the basic physiology of electrolytes and their abnormalities, and the consequences of electrolyte imbalance.
Sodium
Sodium, an osmotically active cation, is one of the essential electrolytes in the extracellular fluid. It is responsible for maintaining the extracellular fluid volume and regulating the membrane potential of cells. Sodium is exchanged along with potassium across cell membranes as part of active transport. [1]
Sodium regulation occurs in the kidneys. The proximal tubule is where the majority of sodium reabsorption takes place. In the distal convoluted tubule, sodium undergoes reabsorption. Sodium transport occurs via sodium-chloride symporters, controlled by the hormone aldosterone.[2]
Among the electrolyte disorders, hyponatremia is the most frequent. Hyponatremia is diagnosed when the serum sodium level is less than 135 mmol/L. Hyponatremia has neurological manifestations.[3] Patients may present with headaches, confusion, nausea, and delirium. Hypernatremia occurs when serum sodium levels are greater than 145 mmol/L. Symptoms of hypernatremia include tachypnea, sleeping difficulty, and restlessness. Rapid sodium corrections can have severe consequences like cerebral edema and osmotic demyelination syndrome (ODS). Other factors like chronic alcohol misuse disorder and malnutrition also play a role in the development of ODS.[4]
Potassium
Potassium is mainly an intracellular ion. The sodium-potassium adenosine triphosphatase pump is primarily responsible for regulating the homeostasis between sodium and potassium, which pumps out sodium in exchange for potassium, which moves into the cells. In the kidneys, the filtration of potassium takes place at the glomerulus. Potassium reabsorption occurs at the proximal convoluted tubule and thick ascending loop of Henle.[5] Potassium secretion occurs at the distal convoluted tubule. Aldosterone increases potassium secretion.[6] Potassium channels and potassium-chloride cotransporters at the apical tubular membrane also secrete potassium.[5]
Potassium derangements may result in cardiac arrhythmias. Hypokalemia occurs when serum potassium levels are under 3.6 mmol/L. The features of hypokalemia include weakness, fatigue, and muscle twitching. Hypokalemic paralysis is generalized body weakness that can be either familial or sporadic.[7] Hyperkalemia occurs when the serum potassium levels are above 5.5 mmol/L, which can result in arrhythmias. Muscle cramps, muscle weakness, rhabdomyolysis, and myoglobinuria may be presenting signs and symptoms of hyperkalemia.[8]
Calcium
Calcium has a significant physiological role in the body. It is involved in skeletal mineralization, contraction of muscles, the transmission of nerve impulses, blood clotting, and secretion of hormones. The diet is the predominant source of calcium. Calcium is a predominately extracellular cation. Calcium absorption in the intestine is primarily controlled by the hormonally active form of vitamin D, which is 1,25-dihydroxy vitamin D3. Parathyroid hormone also regulates calcium secretion in the distal tubule of the kidneys.[9] Calcitonin acts on bone cells to increase the calcium levels in the blood.
Hypocalcemia diagnosis requires checking the serum albumin level to correct for total calcium. Hypocalcemia is diagnosed when the corrected serum total calcium levels are less than 8.8 mg/dL, as in vitamin D deficiency or hypoparathyroidism. Checking serum calcium levels is a recommended test in post-thyroidectomy patients.[10] Hypercalcemia is when corrected serum total calcium levels exceed 10.7 mg/dL, as seen with primary hyperparathyroidism. Humoral hypercalcemia presents in malignancy, primarily due to PTHrP secretion.[11]
Bicarbonate
The acid-base status of the blood drives bicarbonate levels. The kidneys predominantly regulate bicarbonate concentration and maintain the acid-base balance. Kidneys reabsorb the filtered bicarbonate and generate new bicarbonate by net acid excretion, which occurs by the excretion of titrable acid and ammonia. Diarrhea usually results in bicarbonate loss, causing an imbalance in acid-base regulation.[12] Many kidney-related disorders can result in imbalanced bicarbonate metabolism leading to excess bicarbonate in the body.[13]
Magnesium
Magnesium is an intracellular cation. Magnesium is mainly involved in adenosine triphosphate (ATP) metabolism, proper functioning of muscles, neurological functioning, and neurotransmitter release. When muscles contract, calcium re-uptake by the calcium-activated ATPase of the sarcoplasmic reticulum is brought about by magnesium.[14] Hypomagnesemia occurs when the serum magnesium levels are less than 1.46 mg/dL. Alcohol use disorder, gastrointestinal conditions, and excessive renal losses may result in hypomagnesemia. It commonly presents with ventricular arrhythmias, which include torsades de pointes. Hypomagnesemia may also result from the use of certain medications, such as omeprazole.[15]
Chloride
Chloride is an anion found predominantly in the extracellular fluid. The kidneys predominantly regulate serum chloride levels. Most chloride, filtered by the glomerulus, is reabsorbed by both proximal and distal tubules (majorly by proximal tubule) by both active and passive transport.[16]
Hyperchloremia can occur due to gastrointestinal bicarbonate loss. Hypochloremia presents in gastrointestinal losses like vomiting or excess water gain like congestive heart failure.
Phosphorus
Phosphorus is an extracellular fluid cation. Eighty-five percent of the total body phosphorus is in the bones and teeth in the form of hydroxyapatite; the soft tissues contain the remaining 15%. Phosphate plays a crucial role in metabolic pathways. It is a component of many metabolic intermediates and, most importantly, of ATP and nucleotides. Vitamin D3, PTH, and calcitonin regulate phosphate simultaneously with calcium. The kidneys are the primary avenue of phosphorus excretion.
Phosphate imbalance is most commonly due to one of three processes: impaired dietary intake, gastrointestinal disorders, and deranged renal excretion.[17]
Specimen Collection
A blood specimen for electrolytes uses lithium heparin tubes, plus the standard phlebotomy equipment and personnel, as with any blood draw.[18]
Procedures
Blood is collected in lithium heparin tubes and then goes to the laboratory to evaluate serum electrolytes.[18] The collection tubes should not be left for an extended period as cell lysis can occur, causing the intracellular electrolytes and other contents to come out in the serum.
Indications
Indications to order serum electrolyte panels are numerous. Some indications are:
Routine blood investigations
Routine monitoring of hospitalized patients on medications, receiving fluid therapy, undergoing dietary changes, or being treated for ongoing illnesses.
Any illness that can cause electrolyte derangements, such as malnutrition, gastrointestinal disorders, cardiac disorders, kidney dysfunction, endocrine disorders, circulatory disorders, lung disorders, and acid-base imbalance[19]
Arrhythmias
Cardiac arrest
Use of diuretics or any medications that can interfere with fluid and electrolyte homeostasis
Potential Diagnosis
Measurement of electrolytes will help clinicians in the diagnosis of a medical condition, the effectiveness of treatment, and the potential side effect of medications. Examples include:
A patient with heart failure receiving diuretics needs a workup for sodium, potassium, bicarbonate, and magnesium, as diuretics can exert adverse effects on electrolyte balance. [20]
A patient that presents with weakness needs a basic electrolyte workup, as an electrolyte imbalance, especially in sodium and potassium levels, can lead to generalized weakness.
A patient with gastroesophageal reflux disease on long-term proton pump inhibitor therapy should be monitored for hypomagnesemia.
Normal and Critical Findings
Laboratory Values
Serum Sodium
Normal Range: 135 to 145 mmol/L
Mild to moderate hyponatremia: 125 to 135 mmol/L
Severe hyponatremia: less than 125 mmol/L
Mild to moderate hypernatremia: 145 to 160 mmol/L
Severe hypernatremia: greater than 160 mmol/L
Serum Potassium
Normal Range: 3.6 to 5.5 mmol/L
Mild hypokalemia: less than 3.6 mmol/L
Moderate hypokalemia: less than 2.5 mmol/L
Severe hypokalemia: less than greater than 2.5 mmol/L
Mild hyperkalemia: 5 to 5.
5 mmol/L
Moderate hyperkalemia: 5.5 to 6.5 mmol/L
Severe hyperkalemia: 6.5 to 7 mmol/L
Serum Calcium
Normal Range: 8.8 to 10.7 mg/dL
Hypocalcemia: less than 8.8 mg/dL
Mild to moderate hypercalcemia: greater than 10.7 10 11.5 mg/dL
Severe hypercalcemia: greater than 11.5 mg/dL
Serum Magnesium
Normal Range: 1.46 to 2.68 mg/dL
Hypomagnesemia: less than 1.46 mg/dL
Hypermagenesemia: greater than 2.68 mg/dL
Bicarbonate
Normal Range: 23 to 30 mmol/L
It increases or decreases depending on the acid-base status.
Phosphorus
Normal Range: 3.4 to 4.5 mg/dL
Hypophosphatemia: less than 2.5 mg/dL
Hyperphosphatemia: greater than 4.5 mg/dL
Interfering Factors
Factors such as total protein content, hormones, and total body volume status can biochemically influence electrolyte levels. Hypomagnesemia can lead to hypocalcemia due to its effects on parathyroid hormone activity. Intravenous insulin administration is associated with a spurious decrease in potassium levels as insulin shifts potassium intracellularly.[21]
Most serum calcium is bound to proteins; albumin-bound calcium comprises about 80%. Therefore, a patient with hypoalbuminemia, as seen in liver cirrhosis or nephrotic syndrome, will demonstrate artificially abnormal serum calcium levels.[22]
Complications
Hyponatremia, hypernatremia, and hypomagnesemia can lead to neurological consequences such as seizures.
Hypokalemia and hyperkalemia, as well as hypocalcemia, may cause cardiac arrhythmias.[23]
Bicarbonate imbalance can lead to metabolic acidosis or alkalosis.
Some consequences of potassium, calcium, and magnesium abnormalities are fatigue, lethargy, and muscle weakness.
Patient Safety and Education
Patients should be counseled to take all medications exactly as prescribed to avoid any potential adverse effect of electrolyte imbalance. They should also call for immediate medical help if experiencing generalized weakness, muscle aches, or altered mental status.
Clinical Significance
Some of the common causes of electrolyte disorders seen in clinical practices are:
Hyponatremia: low dietary sodium intake, primary polydipsia, syndrome of inappropriate antidiuretic hormone secretion (SIADH), heart failure, cirrhosis, adrenal insufficiency, prolonged hyperglycemia, and severe dyslipidemia.
Hypernatremia: unreplaced fluid loss via the skin or gastrointestinal tract, osmotic diuresis, or hypertonic saline administration.
Hypokalemia: hyperaldosteronism or the use of loop diuretics.
Hyperkalemia: metabolic acidosis, insulin deficiency, hypoaldosteronism, prolonged beta-blocker use, or acute or chronic kidney disease.
Hypercalcemia: malignancy, hyperparathyroidism, or chronic granulomatous diseases such as tuberculosis or sarcoidosis.[24]
Hypocalcemia: acute pancreatitis, iatrogenic parathyroid dysfunction, resistance to parathyroid hormone, hypomagnesemia, or sepsis.
Hypermagnesemia: increased oral magnesium intake.
Hypomagnesemia: increased renal losses with diuretics, alcohol use disorder, or gastrointestinal losses.[25]
Bicarbonate level: increases in primary metabolic alkalosis or compensation to primary respiratory acidosis and decreases in primary metabolic acidosis or compensation to primary respiratory alkalosis.
Hyperchloremia: excessive normal saline infusion.
Hypochloremia: increased gastrointestinal or renal losses.
Hypophosphatemia: refeeding syndrome, vitamin D deficiency, or hyperparathyroidism.[26]
Hyperphosphatemia: hyperparathyroidism or chronic kidney disease.
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Kraut JA, Madias NE. Adverse Effects of the Metabolic Acidosis of Chronic Kidney Disease. Adv Chronic Kidney Dis. 2017 Sep;24(5):289-297. [PubMed: 29031355]
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Jahnen-Dechent W, Ketteler M. Magnesium basics. Clin Kidney J. 2012 Feb;5(Suppl 1):i3-i14. [PMC free article: PMC4455825] [PubMed: 26069819]
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Hansen BA, Bruserud Ø. Hypomagnesemia as a potentially life-threatening adverse effect of omeprazole. Oxf Med Case Reports. 2016 Jul;2016(7):147-9. [PMC free article: PMC4962887] [PubMed: 27471598]
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Disclosure: Isha Shrimanker declares no relevant financial relationships with ineligible companies.
Disclosure: Sandeep Bhattarai declares no relevant financial relationships with ineligible companies.
Electrolytes – StatPearls – NCBI Bookshelf
Introduction
Electrolytes are essential for basic life functioning, such as maintaining electrical neutrality in cells and generating and conducting action potentials in the nerves and muscles. Significant electrolytes include sodium, potassium, chloride, magnesium, calcium, phosphate, and bicarbonates. Electrolytes come from our food and fluids.
These electrolytes can be imbalanced, leading to high or low levels. High or low levels of electrolytes disrupt normal bodily functions and can lead to life-threatening complications. This article reviews the basic physiology of electrolytes and their abnormalities, and the consequences of electrolyte imbalance.
Sodium
Sodium, an osmotically active cation, is one of the essential electrolytes in the extracellular fluid. It is responsible for maintaining the extracellular fluid volume and regulating the membrane potential of cells. Sodium is exchanged along with potassium across cell membranes as part of active transport.[1]
Sodium regulation occurs in the kidneys. The proximal tubule is where the majority of sodium reabsorption takes place. In the distal convoluted tubule, sodium undergoes reabsorption. Sodium transport occurs via sodium-chloride symporters, controlled by the hormone aldosterone.[2]
Among the electrolyte disorders, hyponatremia is the most frequent. Hyponatremia is diagnosed when the serum sodium level is less than 135 mmol/L. Hyponatremia has neurological manifestations.[3] Patients may present with headaches, confusion, nausea, and delirium. Hypernatremia occurs when serum sodium levels are greater than 145 mmol/L. Symptoms of hypernatremia include tachypnea, sleeping difficulty, and restlessness. Rapid sodium corrections can have severe consequences like cerebral edema and osmotic demyelination syndrome (ODS). Other factors like chronic alcohol misuse disorder and malnutrition also play a role in the development of ODS.[4]
Potassium
Potassium is mainly an intracellular ion. The sodium-potassium adenosine triphosphatase pump is primarily responsible for regulating the homeostasis between sodium and potassium, which pumps out sodium in exchange for potassium, which moves into the cells. In the kidneys, the filtration of potassium takes place at the glomerulus. Potassium reabsorption occurs at the proximal convoluted tubule and thick ascending loop of Henle.[5] Potassium secretion occurs at the distal convoluted tubule. Aldosterone increases potassium secretion.[6] Potassium channels and potassium-chloride cotransporters at the apical tubular membrane also secrete potassium.[5]
Potassium derangements may result in cardiac arrhythmias. Hypokalemia occurs when serum potassium levels are under 3. 6 mmol/L. The features of hypokalemia include weakness, fatigue, and muscle twitching. Hypokalemic paralysis is generalized body weakness that can be either familial or sporadic.[7] Hyperkalemia occurs when the serum potassium levels are above 5.5 mmol/L, which can result in arrhythmias. Muscle cramps, muscle weakness, rhabdomyolysis, and myoglobinuria may be presenting signs and symptoms of hyperkalemia.[8]
Calcium
Calcium has a significant physiological role in the body. It is involved in skeletal mineralization, contraction of muscles, the transmission of nerve impulses, blood clotting, and secretion of hormones. The diet is the predominant source of calcium. Calcium is a predominately extracellular cation. Calcium absorption in the intestine is primarily controlled by the hormonally active form of vitamin D, which is 1,25-dihydroxy vitamin D3. Parathyroid hormone also regulates calcium secretion in the distal tubule of the kidneys.[9] Calcitonin acts on bone cells to increase the calcium levels in the blood.
Hypocalcemia diagnosis requires checking the serum albumin level to correct for total calcium. Hypocalcemia is diagnosed when the corrected serum total calcium levels are less than 8.8 mg/dL, as in vitamin D deficiency or hypoparathyroidism. Checking serum calcium levels is a recommended test in post-thyroidectomy patients.[10] Hypercalcemia is when corrected serum total calcium levels exceed 10.7 mg/dL, as seen with primary hyperparathyroidism. Humoral hypercalcemia presents in malignancy, primarily due to PTHrP secretion.[11]
Bicarbonate
The acid-base status of the blood drives bicarbonate levels. The kidneys predominantly regulate bicarbonate concentration and maintain the acid-base balance. Kidneys reabsorb the filtered bicarbonate and generate new bicarbonate by net acid excretion, which occurs by the excretion of titrable acid and ammonia. Diarrhea usually results in bicarbonate loss, causing an imbalance in acid-base regulation.[12] Many kidney-related disorders can result in imbalanced bicarbonate metabolism leading to excess bicarbonate in the body. [13]
Magnesium
Magnesium is an intracellular cation. Magnesium is mainly involved in adenosine triphosphate (ATP) metabolism, proper functioning of muscles, neurological functioning, and neurotransmitter release. When muscles contract, calcium re-uptake by the calcium-activated ATPase of the sarcoplasmic reticulum is brought about by magnesium.[14] Hypomagnesemia occurs when the serum magnesium levels are less than 1.46 mg/dL. Alcohol use disorder, gastrointestinal conditions, and excessive renal losses may result in hypomagnesemia. It commonly presents with ventricular arrhythmias, which include torsades de pointes. Hypomagnesemia may also result from the use of certain medications, such as omeprazole.[15]
Chloride
Chloride is an anion found predominantly in the extracellular fluid. The kidneys predominantly regulate serum chloride levels. Most chloride, filtered by the glomerulus, is reabsorbed by both proximal and distal tubules (majorly by proximal tubule) by both active and passive transport. [16]
Hyperchloremia can occur due to gastrointestinal bicarbonate loss. Hypochloremia presents in gastrointestinal losses like vomiting or excess water gain like congestive heart failure.
Phosphorus
Phosphorus is an extracellular fluid cation. Eighty-five percent of the total body phosphorus is in the bones and teeth in the form of hydroxyapatite; the soft tissues contain the remaining 15%. Phosphate plays a crucial role in metabolic pathways. It is a component of many metabolic intermediates and, most importantly, of ATP and nucleotides. Vitamin D3, PTH, and calcitonin regulate phosphate simultaneously with calcium. The kidneys are the primary avenue of phosphorus excretion.
Phosphate imbalance is most commonly due to one of three processes: impaired dietary intake, gastrointestinal disorders, and deranged renal excretion.[17]
Specimen Collection
A blood specimen for electrolytes uses lithium heparin tubes, plus the standard phlebotomy equipment and personnel, as with any blood draw. [18]
Procedures
Blood is collected in lithium heparin tubes and then goes to the laboratory to evaluate serum electrolytes.[18] The collection tubes should not be left for an extended period as cell lysis can occur, causing the intracellular electrolytes and other contents to come out in the serum.
Indications
Indications to order serum electrolyte panels are numerous. Some indications are:
Routine blood investigations
Routine monitoring of hospitalized patients on medications, receiving fluid therapy, undergoing dietary changes, or being treated for ongoing illnesses.
Any illness that can cause electrolyte derangements, such as malnutrition, gastrointestinal disorders, cardiac disorders, kidney dysfunction, endocrine disorders, circulatory disorders, lung disorders, and acid-base imbalance[19]
Arrhythmias
Cardiac arrest
Use of diuretics or any medications that can interfere with fluid and electrolyte homeostasis
Potential Diagnosis
Measurement of electrolytes will help clinicians in the diagnosis of a medical condition, the effectiveness of treatment, and the potential side effect of medications. Examples include:
A patient with heart failure receiving diuretics needs a workup for sodium, potassium, bicarbonate, and magnesium, as diuretics can exert adverse effects on electrolyte balance.[20]
A patient that presents with weakness needs a basic electrolyte workup, as an electrolyte imbalance, especially in sodium and potassium levels, can lead to generalized weakness.
A patient with gastroesophageal reflux disease on long-term proton pump inhibitor therapy should be monitored for hypomagnesemia.
Normal and Critical Findings
Laboratory Values
Serum Sodium
Normal Range: 135 to 145 mmol/L
Mild to moderate hyponatremia: 125 to 135 mmol/L
Severe hyponatremia: less than 125 mmol/L
Mild to moderate hypernatremia: 145 to 160 mmol/L
Severe hypernatremia: greater than 160 mmol/L
Serum Potassium
Normal Range: 3.6 to 5.5 mmol/L
Mild hypokalemia: less than 3.
6 mmol/L
Moderate hypokalemia: less than 2.5 mmol/L
Severe hypokalemia: less than greater than 2.5 mmol/L
Mild hyperkalemia: 5 to 5.5 mmol/L
Moderate hyperkalemia: 5.5 to 6.5 mmol/L
Severe hyperkalemia: 6.5 to 7 mmol/L
Serum Calcium
Normal Range: 8.8 to 10.7 mg/dL
Hypocalcemia: less than 8.8 mg/dL
Mild to moderate hypercalcemia: greater than 10.7 10 11.5 mg/dL
Severe hypercalcemia: greater than 11.5 mg/dL
Serum Magnesium
Normal Range: 1.46 to 2.68 mg/dL
Hypomagnesemia: less than 1.46 mg/dL
Hypermagenesemia: greater than 2.68 mg/dL
Bicarbonate
Normal Range: 23 to 30 mmol/L
It increases or decreases depending on the acid-base status.
Phosphorus
Normal Range: 3.4 to 4.5 mg/dL
Hypophosphatemia: less than 2.
5 mg/dL
Hyperphosphatemia: greater than 4.5 mg/dL
Interfering Factors
Factors such as total protein content, hormones, and total body volume status can biochemically influence electrolyte levels. Hypomagnesemia can lead to hypocalcemia due to its effects on parathyroid hormone activity. Intravenous insulin administration is associated with a spurious decrease in potassium levels as insulin shifts potassium intracellularly.[21]
Most serum calcium is bound to proteins; albumin-bound calcium comprises about 80%. Therefore, a patient with hypoalbuminemia, as seen in liver cirrhosis or nephrotic syndrome, will demonstrate artificially abnormal serum calcium levels.[22]
Complications
Hyponatremia, hypernatremia, and hypomagnesemia can lead to neurological consequences such as seizures.
Hypokalemia and hyperkalemia, as well as hypocalcemia, may cause cardiac arrhythmias.[23]
Bicarbonate imbalance can lead to metabolic acidosis or alkalosis.
Some consequences of potassium, calcium, and magnesium abnormalities are fatigue, lethargy, and muscle weakness.
Patient Safety and Education
Patients should be counseled to take all medications exactly as prescribed to avoid any potential adverse effect of electrolyte imbalance. They should also call for immediate medical help if experiencing generalized weakness, muscle aches, or altered mental status.
Clinical Significance
Some of the common causes of electrolyte disorders seen in clinical practices are:
Hyponatremia: low dietary sodium intake, primary polydipsia, syndrome of inappropriate antidiuretic hormone secretion (SIADH), heart failure, cirrhosis, adrenal insufficiency, prolonged hyperglycemia, and severe dyslipidemia.
Hypernatremia: unreplaced fluid loss via the skin or gastrointestinal tract, osmotic diuresis, or hypertonic saline administration.
Hypokalemia: hyperaldosteronism or the use of loop diuretics.
Hyperkalemia: metabolic acidosis, insulin deficiency, hypoaldosteronism, prolonged beta-blocker use, or acute or chronic kidney disease.
Hypercalcemia: malignancy, hyperparathyroidism, or chronic granulomatous diseases such as tuberculosis or sarcoidosis.[24]
Hypocalcemia: acute pancreatitis, iatrogenic parathyroid dysfunction, resistance to parathyroid hormone, hypomagnesemia, or sepsis.
Hypermagnesemia: increased oral magnesium intake.
Hypomagnesemia: increased renal losses with diuretics, alcohol use disorder, or gastrointestinal losses.[25]
Bicarbonate level: increases in primary metabolic alkalosis or compensation to primary respiratory acidosis and decreases in primary metabolic acidosis or compensation to primary respiratory alkalosis.
Hyperchloremia: excessive normal saline infusion.
Hypochloremia: increased gastrointestinal or renal losses.
Hypophosphatemia: refeeding syndrome, vitamin D deficiency, or hyperparathyroidism.
[26]
Hyperphosphatemia: hyperparathyroidism or chronic kidney disease.
Review Questions
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References
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Disclosure: Isha Shrimanker declares no relevant financial relationships with ineligible companies.
Disclosure: Sandeep Bhattarai declares no relevant financial relationships with ineligible companies.
Theory of electrolytic dissociation (TED) – what is it? Key points and examples
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A solution of sodium chloride conducts electricity well, but when dry, salt crystals do not conduct electricity. Why? This question is answered by the theory of electrolytic dissociation, which we will now consider. It was first described by the Swedish scientist Svante Arrhenius. Electrolytic dissociation is studied as part of a chemistry course for 9Class.
What is electrolytic dissociation
As you know, electric current is a directed movement of free electrons or ions, ie charged particles. In electrolyte solutions that conduct current, free ions are responsible for this.
In 1882, the Swedish chemist S. Arrhenius, while studying the properties of electrolyte solutions, noticed that they contain more particles than were in the dry matter. For example, in a solution of sodium chloride, there are 2 moles of particles, while dry NaCl contains only 1 mole.
This allowed the scientist to conclude that when such substances are dissolved in water, free ions appear in them. Thus, the foundations of the theory of electrolytic dissociation (TED) were laid – in chemistry it became one of the most important discoveries.
Electrolytic dissociation is the process by which electrolyte molecules react with water or another solvent and break down into ions. It may be reversible or irreversible. The reverse process is called molarization.
Electrolyte solutions become conductive through dissociation. Svante Arrhenius could not explain why different substances differ greatly in electrical conductivity, but D. I. Mendeleev did this. He described in detail the process of decomposition of an electrolyte into ions, which is explained by its interaction with water molecules (or other solvent).
Electrolytic dissociation scheme: KA ⇄ K + (cation) + A – (anion).
Dissociation equation using sodium chloride as an example: NaCl ⇄ Na + + Cl – .
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Sometimes you can come across the expression “electrical dissociation theory”, but you shouldn’t say that. In this case, one might think that the disintegration of molecules into ions is due to the action of an electric current. In fact, the dissociation process does not depend on whether current is currently passing through the solution or not. All that is needed is the contact of the electrolyte with water (solvent).
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Mechanism of electrolytic dissociation
When in contact with water or other solvents, all substances with an ionic bond are subject to dissociation. Substances with a covalent polar bond can also decompose into ions, which, under the action of water, becomes ionic, and then collapses.
It is convenient to consider the mechanism of electrolyte dissociation using sodium chloride NaCl as an example. Its crystal lattice is formed by sodium cations Na + and chlorine anions Cl – , which are held together by ionic bonding. When dissolved in water, each crystal of sodium chloride is surrounded by its molecules.
Note that water molecules are dipoles. At one end they carry hydrogen atoms with a partial positive charge, and at the other end they carry oxygen atoms with a partial negative charge. Accordingly, oxygen atoms are attracted to sodium cations, and hydrogen atoms are attracted to chlorine anions. This electrostatic attraction weakens and eventually breaks the ionic bond between sodium and chloride. A substance dissociates into ions.
After the decomposition of sodium chloride, the resulting Na + and Cl – ions surround water molecules, creating a hydration shell . Ions with such a shell are called hydrated.
If another solvent, such as ethanol, was used instead of water, its molecules form a solvation shell . In this case, the ions are called solvated.
The scheme conveys the essence of the electrolytic dissociation process:
Electrolytes and non-electrolytes
Although electrolytic dissociation occurs independently of the action of an electric current, there is a connection between these phenomena. The higher the ability of a substance to decompose into ions when interacting with a solvent, the better it conducts electricity. According to this criterion, the famous physico-chemist M. Faraday singled out electrolytes and non-electrolytes.
Electrolytes are substances that, after dissociation into ions in solutions and melts, conduct an electric current. Usually in their molecules there are ionic or polar covalent bonds.
Non-electrolytes are substances that do not decompose into ions in solutions and melts, and therefore do not have conductivity in dissolved form. They are characterized by covalent non-polar or weakly polar bonds.
Degree of dissociation
Depending on how many molecules have dissociated into ions, the substance can be a strong or weak electrolyte. This indicator is called the degree of dissociation, it is measured from 0 to 1 or as a percentage.
The degree of dissociation is the ratio of the number of moles of a substance decomposed into ions to the initial number of moles.
or .
If all 100% of the electrolyte decomposes into ions in solution, .
By strength, electrolytes are divided into the following groups:
weak – ;
medium – ;
strong — .
Important!
Molecules of strong electrolytes irreversibly decompose into ions, so the sign = must be put in the equations. Reactions with weak electrolytes are reversible, so the sign ⇄ is put.
Stepwise dissociation
In some cases, substances are split into ions in several stages or steps. For example, such a reaction is typical for basic and acidic salts, polybasic acids. Stepwise dissociation can include two or more stages, with the ion concentration at the first stage always higher than at the subsequent ones.
Example 1
Phosphoric acid dissociates in 3 steps. On the first of them, the maximum concentration of dihydrophosphate ions is observed, and on the last one, the minimum amount of phosphate ions remains (dissociation almost does not occur). This acid is not a strong electrolyte, so the reaction is reversible.
H 3 PO 4 3
H 2 PO 4 – ⇄ H + + HPO
HPO 4 2- ⇄ H + + PO 4 3-
Summary equation: H 3 PO 4 ⇄ 3H + + PO 4 3- .
Example 2
The acid salt Ca(HCO 3 ) 2 dissociates in 3 steps. Because it is a strong electrolyte, the reaction is irreversible in the first step. At the second stage, a weak acid residue HCO 3 – and a weak electrolyte decompose into ions, so the reaction is reversible.
Ca(HCO 3 ) 2 = Ca 2+ + 2HCO
HCO 3 – ⇄ H + + CO 3 2-
H + + H 2 O = H 3 O +
Summary equation: Ca(HCO 3 ) 2 + 2H 2 O = Ca 2+ + 2H CO 3 2- .
How different groups of substances dissociate
Dissociation of acids
Leads to the formation of hydrogen cations H + and negatively charged acid residues:
HCl = H + + Cl –
H 2 SO 4 = 2H 024 + SO 4 2-
HNO 2 ⇄ H + + NO 2-
Polybasic acids dissociate stepwise:
AlOHCl AlOH 2+ + 2Cl –
AlOH 2+ ⇄ Al 3+ + OH –
Base dissociation
Occurs with the formation of hydroxyl groups OH – and positively charged metal ions. Strong electrolytes in solutions dissociate completely, while weak electrolytes dissociate stepwise and reversibly.
Strong bases:
NaOH = Na + + OH 0010 Cu(ON) 2 ⇄ CuOH + + OH –
CuOH + ⇄ Cu 2+ + OH –
Dissociation of salts
Leads to the formation of metal cations (or ammonium cation) and negatively charged acid residues.
Medium salts completely decompose in solutions in one step.
Na 3 PO 4 = 3Na + PO 4 3-
Acid salts decompose stepwise. At the first stage, metal cations are separated, and at the second stage, hydrogen cations.
KHSO 4 = K + + HSO 4 –
HSO 4 – ⇄ H + + SO 4 2-
Basic salts also dissociate in two steps. At the first, acid residues are separated, followed by hydroxyl groups OH – .
MgOHBr = MgOH + + Br –
MgOH + ⇄ Mg 2+ + OH –
Molecular, complete and abbreviated ionic equations
Molecular equations can be used to show the composition of a substance by decomposing it into molecules. The complete ionic equations reflect the dissociation reaction, i.e., the splitting of molecules into ions. But in this form, only strong electrolytes are painted.
Do not decompose into ions:
weak electrolytes;
precipitation;
gases.
Consider the example of the interaction between lead nitrate and sulfuric acid.
Molecular equation: Pb(NO 3 ) 2 + H 2 SO 4 → 2HNO 3 + PbSO 901 31 4 ↓
Lead sulfate PbSO 4 9We will not decompose 0132 into ions, since it is a weak electrolyte.
Full ionic equation: Pb 2+ + 2NO 3 – + 2H + + SO 4 2- → 2H + + 2NO 3 – + PbSO 4 ↓
It is very easy to reduce this expression – you need to remove the same ions from both parts that have not changed during the reaction.
Abbreviated ionic equation: Pb 2+ + SO 4 2- → PbSO 4 ↓
are the formulas of the formed cations and anions. Between them we put the sign = if it is a strong electrolyte, or the sign ⇄ – if it is medium or weak. After that, you need to put down the coefficients in front of the ions and check the sum of cations and anions (it is always equal to 0).
Fundamentals of the theory of electrolytic dissociation
So, we figured out what dissociation is in chemistry, and now we will repeat the key points:
When interacting with water or other solvents in electrolytes, the chemical bond between particles is broken and they decompose into ions – electrolytic dissociation occurs.
Under the action of an electric current, cations move to a positively charged electrode, anions – to a negatively charged one.
The electrolyte solution is conductive.
The degree of dissociation depends on the type of electrolyte and on external conditions. For strong electrolytes, it is irreversible; for weak electrolytes, it is a reversible reaction.
The chemical properties of electrolytes correspond to the properties of the ions formed during dissociation.
Self-test questions
How do electrolytes differ from non-electrolytes? Give examples of both substances.
According to the theory of dissociation, what causes the decomposition of electrolytes into ions?
What is the degree of dissociation and how is it measured?
When does the electrolytic dissociation of acids occur in steps?
Under what conditions is the = sign put in the dissociation equation, and under what conditions is the ⇄ sign?
Which components of an ionic equation cannot be decomposed into ions?
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Electrolytic dissociation of electrolytes in aqueous solutions
On this page you will learn
- Is there any connection between electronics and electrolytes?
- What kind of chemistry occurs during tea drinking?
- Human attention concentration formula “Good sleep + proper nutrition + sports”.
What is the formula for the concentration of solutions?
“Probably, here they will talk about electricity and water, and about some associations. What is all this?!” If almost all the words in the title of this article are not yet clear to you, do not panic. In this article, we will deal with all the new terms.
About electrolytes
What is electrolytic dissociation?
It sounds abstruse, but in fact there is nothing terrible or complicated in this definition.
Electrolytic dissociation – the decomposition of some substance (electrolyte) into ions (charged particles).
Electrolyte is a substance that, when released into water, will decompose into ions, that is, dissociate, and conduct current in melts and solutions.
Is there any connection between electronics and electrolytes? Yes! And it lies not only in the same beginning of the names of these words, but also in the fact that these substances are directly related to current and electricity. |
It is important to remember that some electrolytes are able to break down into ions well (they are called strong ), and some are almost not able to do this (they are called weak ). In this, ions are like athletes: one can squeeze out more than 50 times in a minute (break up into many ions), and the other barely squeezes out ten (almost no ions). People will quickly define the first as strong, and the second, alas, as weak.
It is easiest to remember first those who are classified as strong electrolytes, then all the rest will be weak.
Which classes of substances are classified as electrolytes?
- Salts.
- Bases.
- Acids.
We memorize by the first letters that make up the code word “SOK”.
About solutions
Dissolution of is a physical and chemical process in which particles interact with each other.
What chemistry occurs during tea drinking? When we add sugar to tea, we can observe how sugar molecules interact with tea molecules, due to which the substance dissolves in water, and a sweet solution is formed. |
What is a solution? Solution is a homogeneous system consisting of two or more components. For example: air (consists of different gases), oil (a mixture of liquid hydrocarbons), vinegar (a solution of acetic acid in water).
There are also supersaturated solutions , in which more substance is dissolved than the maximum possible. Therefore, they are very unstable.
It is important to note that the substance that predominates in the solution is thinner . Most often, water is used as a solvent. |
What else is important to know about solutions – they have a certain concentration.
Concentration of a solution is the amount of a substance that is in a unit volume or mass of a solution.
Human attention concentration formula = “Good sleep + proper nutrition + sports”. What is the formula for the concentration of solutions? The most commonly used formula for expressing the concentration of a solution is: C m – concentration of the solution Also, the concentration can be expressed as follows: |
- Electrolytic dissociation – decomposition of some substance (electrolyte) into ions (charged particles).
- Electrolyte is a substance that, when released into water, will decompose into ions, that is, dissociate, and conduct current in melts and solutions.
- Three classes of substances are classified as electrolytes: salts, bases and acids.