What Are Electrolytes?

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Main Category: Blood / Hematology
Also Included In: Endocrinology;  Urology / Nephrology;  Sports Medicine / Fitness
Article Date: 09 Jun 2009 - 9:00 PDT

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An electrolyte is "any compound that, in solution or in molten form, conducts electricity and is decomposed (electrolyzed) by it. It is an ionizable substance in solution" (Medilexicon's medical dictionary). An electrolyte is any substance that contains free ions that behaves as an electrically conductive medium (conducts electricity). All higher forms of life cannot exist without electrolytes, and that includes humans.

In our bodies, electrolytes include sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), bicarbonate (HCO₃^-, magnesium (Mg²⁺), chloride (C1^-), hydrogen phosphate (HPO₄^2-), and hydrogen carbonate (HCO₃^-). Electrolytes regulate our nerve and muscle function, our body's hydration, blood pH, blood pressure, the rebuilding of damaged tissue. Various mechanisms exist in our body that keep the concentrations of different electrolytes under strict control.

Our muscles and neurons are thought of as electric tissues of the body. They are activated by electrolyte activity between extracellular fluid or interstitial fluid, and intracellular fluid (fluid inside and outside or between cells).

A muscle contraction needs calcium (Ca²⁺), sodium (Na⁺) and potassium (K⁺) to be present. If levels of vital electrolytes are wrong, the muscles either become too weak, or their contractions are too severe. Our heart, muscle and nerve cells use electrolytes to maintain voltages across their cell membranes to carry electrical impulses across themselves and to other cells.

The level of an electrolyte in the blood can become too high or too low. Body electrolyte levels tend to change when water levels in the body change - when our level of hydration is altered.

Electrolyte levels are kept constant by our kidneys and various hormones - even when our bodies trigger changes. When we exercise we sweat and lose electrolytes, mainly sodium and potassium. To maintain electrolyte concentrations of our body fluids constant these electrolytes must be replaced. Fresh fruits and vegetables are good sources of sodium and potassium and replace lost electrolytes. Excess electrolyte levels in our blood are filtered out by our kidney.

If our consumption of necessary electrolytes is wrong there can be health consequences. The most common imbalances are hypernatremia and hyponatremia - too much or too little sodium, and hyper kalemia and hypokalemia, or excessive and insufficient levels of potassium. Doctors refer to a low electrolyte level with the prefix hypo- and to a high level with the prefix hyper-.

Elderly people and electrolyte levels

As older people are more susceptible to dehydration and overhydration, they are also more prone to abnormal electrolyte levels. This is because our kidneys do not work so well when we become elderly. Some elderly people who have mobility problems and do not have daily access to some help may have fluctuating levels of food and fluid intake - these two factors can have an impact on their levels of electrolytes.

What are the symptoms of electrolyte imbalance?

An electrolyte imbalance can lead to several symptoms. The symptoms will depend on which electrolyte is out of balance, and whether that level is too high or low. An altered level of magnesium, sodium, potassium, or calcium may produce one or more of the following symptoms:

• Weakness
• Twitching
• Seizures
• Numbness
• Nervous system disorders
• Muscle spasm
• Fatigue, lethargy
• Irregular heartbeat
• Convulsions
• Confusion
• Bone disorders
• Blood pressure changes

High blood calcium is a common problem among cancer patients

Hypercalcemia is a common disorder among cancer patients, especially those with breast cancer, lung cancer and multiple myeloma. It often results from the destruction of bone due to bone metastases. Signs and symptoms may include:

• Frequent urination
• Irregular heart beat
• Lethargy, fatigue
• Moodiness and irritability
• Nausea
• Stomach pain
• Vomiting
• Extreme muscle weakness
• Being extremely thirsty
• Dry mouth or throat
• Total loss of appetite
• Coma
• Confusion
• Constipation

As these symptoms may also be the result of the cancer itself or cancer treatment, it is sometimes difficult for hypercalcemia to be identified straight away.

What cause electrolyte imbalances?

• Kidney disease


• Vomiting for prolonged periods


• Severe dehydration


• Heatwaves - A report found that the number of cases of electrolyte imbalances increases significantly during heatwaves.


• Acid/base (pH) imbalance (acid and alkaline balance in the body is disproportionate)


• Congestive heart failure


• Cancer treatment


• Some drugs, such as diuretics or ACE inhibitors. A study revealed that 20% of patients taking diuretics commonly prescribed for high blood pressure or heart conditions end up with reduced sodium and potassium levels


• Bulimia (eating and purging meals, it is an eating disorder)


• Severe and persistent vomiting and nausea during pregnancy.

Many sports drinks contain extra potassium and sodium to help restore lost electrolytes which are lost through sports or intense physical exertion. Experts say it is not ideal to consume just large quantities of water after we exercise heavily because our existing electrolyte levels may drop too quickly. The Academy of Orthopaedic Surgeons (UK) has some tips on preventing cramps.

When children suffer from vomiting and/or diarrhea they will need to replenish their electrolytes. There are drinks in pharmacies targeted specifically for such children. A study found that Pedialyte and Gatorade equally effective in alleviating effects of viral gastroenteritis in children. Another study published in the May issue of Archives of Disease in Childhood advises that children with acute vomiting and diarrhea should not use 'flat' carbonated beverages as an alternative for oral rehydration solution. An interesting article by Johns Hopkins Medicine states that any childhood athletic activity that lasts less than 60 minutes doesn't require electrolytes, so you can safely skip electrolyte-enriched sports drinks.

What are high- low- calcium, potassium and sodium levels?

• Low sodium levels (hyponatremia) - Hyponatremia may result from not eating enough foods with sodium, too much sweating and urinating, or being overhydrated. When large amounts of fluids, which do not contain sodium, are given intravenously the patient may develop hyponatremia. Diuretics make the kidneys get rid of excess sodium and water faster - sometimes the excretion of sodium is faster than the excretion of water. When sodium levels are low our bodies can produce too much of an antidiuretic hormone which tells our kidneys to retain water - this commonly happens in patients who have pneumonia, stroke, and those taking certain medications, such as anticonvulsants and some SSRI antidepressants.
  
  Patients with diabetes, heart failure, liver failure and kidney disorders can also suffer from low sodium levels. People suffering from hyponatremia may experience, confusion, headache, irritability, loss of appetite, muscle weakness, nausea, vomiting, fatigue, decreased consciousness, and even hallucinations and coma. A study explains that athletes who drink excessive amounts of fluids during prolonged exercise-particularly novice marathon runners-can develop dangerously low sodium levels


• High sodium levels (hypernatremia) - This is usually caused by water loss (dehydration) or the use of diuretics. Diuretics can cause both hyponatremia and hypernatremia. The first symptom of hypernatremia is thirst. Typically, patients with hypernatremia feel weak and sluggish. When levels are too high people can suffer from confusion, paralysis, seizures and coma. The best treatment is to increase water intake - sometimes this is done intravenously.


• Low potassium levels (hypokalemia) - This is often caused by using diuretics. Diuretics tend to make the kidneys excrete more potassium and water in urine. Diarrhea and vomiting can also cause hypokalemia. If potassium levels drop slightly no symptoms are usually experienced. Prolonged slightly low potassium levels usually results in lower insulin production, resulting in an increase in blood sugar levels. If levels drop too low the patient will suffer from fatigue, confusion, muscle weakness and cramps. If levels get too low the person can become paralyzed, and have arrhythmias (unusual heart rhythms). Patients with heart failure who take digoxin and have moderately low potassium levels tend to develop abnormal heart rhythms. An interesting article looks at the benefits of diuretics for heart failure patients, while others wonder whether the change in electrolyte levels might not outweigh the benefits.
  
  Low potassium is treated with potassium supplements by mouth - this can be either in tablet or liquid forms. Patients can also raise their potassium levels by changing their diet. Hypokalemia caused by diuretics can sometimes be resolved by switching to a potassium-sparing diuretic. This interesting article explores why cystic fibrosis patients may be prone to low potassium levels.


• High potassium levels (hyperkalemia) - This is much more serious than hypokalemia. Hyperkalemia is usually caused by either kidney failure or some medications that lower the amount of potassium excreted by the kidneys, such as the diuretic spironolactone, and angiotensin-converting enzyme (ACE) inhibitors which are used for hypertension (high blood pressure). Patients taking these medications combined with potassium supplements or food high in potassium tend to have rapidly increasing potassium levels because their kidneys cannot get rid of it fast enough. They should stop taking the potassium supplements and change their diets. In some cases drugs that speed up the excretion of potassium are needed. Those with abnormal heart rhythms may be given calcium intravenously. Heart drugs can cause dangerous build up of potassium.


• Low calcium levels (hypocalcemia) - This can happen as a result of a sudden widespread blood infection, as well as infection in other tissues. If the body produces less parathyroid hormone the calcium levels can also drop - this may be the result after the removal of the parathyroid glands during neck surgery. People with vitamin D deficiency are more prone to hypocalcemia. The main reasons for low vitamin D are not enough exposure to sunlight and diet. Other reasons for vitamin D deficiency may include anticonvulsant medications, such as phenytoin and phenobarbital, or an underactive thyroid gland. People with hypocalcemia may experience numbness in the hands and/or feet, confusion, and even seizures. Treatment includes taking oral calcium supplements, and treating the disorder that caused it.


• High calcium levels (hypercalcemia) - This can happen if a bone is broken down and calcium is released into the bloodstream. When cancer spreads to the bone there may be calcium release into the bloodstream. In severe cases of Paget's disease hypercalcemia can become very debilitating. If levels of parathyroid hormone are too high hypercalcemia is much more likely - this is usually the result of a tumor in the parathyroid gland. Some cancers may cause parathyroid hormone levels to rise too much. If thyroid hormone levels are abnormally high calcium levels can rise excessively.
  
  If calcium levels rise slightly most people do not have any symptoms. If levels are higher the patient will experience dehydration because the kidneys will automatically start excreting more water. When levels are very high the patient will experience nausea, loss of appetite, vomiting and confusion. There is also a risk of coma and death. Very high levels of calcium need to be treated immediately.

What is an electrolyte panel (electrolyte test)?

An electrolyte panel is sometimes done as part of a routine physical. It can be done as it is or as part of a basic metabolic panel or comprehensive metabolic panel. The test is used to screen for any electrolyte or acid-base imbalance (the body's balance between acidity and alkalinity) and to check the effect of treatment on a known imbalance that is affecting the bodily function of an organ. The electrolyte panel is often used with hospitalized patients or those who are brought to the emergency room - this is because acid-base and electrolyte imbalances are frequently part of acute and chronic illnesses.

If a single electrolyte is found to be either too high or too low, the doctor will keep testing for that imbalance until levels are back to normal. If an acid-base imbalance is found, blood gas tests may be done. These measure the pH, oxygen and carbon dioxide levels in an arterial blood sample to determine how severe the imbalance is and see how the patient responds to treatment. Electrolytes may also be tested if the patient is prescribed certain drugs, especially diuretics or ACE inhibitors.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today