Electrolyte
ELECTROLYTE BLOOD TESTS – SODIUM, POTASSIUM, CHLORIDE & BICARBONATE
Question 1. What are Electrolytes
Electrolyte is a "medical/scientific" term for salts, specifically ions. The term electrolyte means that this ion is electrically-charged and moves to either a negative (cathode) or positive (anode) electrode: i.e. electrolytes are substances in our body have capacity to conduct electricity between outside cells (extracellular) and inside cells (intracellular). The balance of the electrolytes in our bodies is essential for normal function of our cells and our organs.
Medically, blood or serum measurement of electrolytes commonly refers the following: sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+), magnesium (Mg2+), bicarbonate (HCO3-) & phosphate (PO42-).
Question 2. What are the roles of electrolytes in my body?
Electrolytes are important because they are what your cells (especially nerve, heart, muscle) use to maintain voltages across their cell membranes and to carry electrical impulses (nerve impulses, muscle contractions) across themselves and to other cells. Your kidneys work to keep the electrolyte concentrations in your blood constant despite changes in your body. For example, when you exercise heavily, you lose electrolytes in your sweat, particularly sodium and potassium. These electrolytes must be replaced to keep the electrolyte concentrations of your body fluids constant. So, many sports drinks have sodium chloride or potassium chloride added to them. They also have sugar and flavourings to provide your body with extra energy and to make the drink taste better.
Specific functions and normal range values for common electrolytes measured are described below.
Sodium:
Sodium is the major positive ion (cation) in fluid outside of cells. The chemical notation for sodium is Na+. When combined with chloride, the resulting substance is table salt. Excess sodium (such as from fast food hamburger and fries) is excreted in the urine. Sodium regulates the total amount of water in the body and the transmission of sodium into and out of individual cells also plays a role in critical body functions. Many processes in the body, especially in the brain, nervous system, and muscles, require electrical signals for communication. The movement of sodium is critical in generation of these electrical signals. Too much or too little sodium therefore can cause cells to malfunction, and extremes (too much or too little) can be fatal. A Normal blood sodium level is 135 - 145milliEquivalents/litre (mEq/L), or in international units, 135 - 145millimoles/liter (mmol/L).
Potassium:
Potassium is the major positive ion (cation) found inside of cells. The chemical notation for potassium is K+. The proper level of potassium is essential for normal cell function. Among the many functions of potassium in the body are regulation of the heartbeat and function of the muscles. A seriously abnormal increase of potassium (hyperkalemia) or decrease of potassium (hypokalemia) can profoundly affect the nervous system and increases the chance of irregular heartbeats (arrhythmias), which, when extreme, can be fatal.
The normal blood potassium level is 3.5 - 5.0milliEquivalents/liter (mEq/L), or in international units, 3.5 - 5.0millimoles/liter (mmol/L).
Chloride:
Chloride is the major anion (negatively charged ion) found in the fluid outside of cells and in blood. An anion is the negatively charged part of certain substances such as table salt (sodium chloride or NaCl) when dissolved in liquid. Sea water has almost the same concentration of chloride ion as human fluids. Chloride also plays a role in helping the body maintain a normal balance of fluids.
The balance of chloride ion (Cl-) is closely regulated by the body. Significant increases or decreases in chloride can have deleterious or even fatal consequences:
Increased chloride (hyperchloremia): Elevations in chloride may be seen in diarrhoea, certain kidney diseases, and sometimes in overactivity of the parathyroid glands.
Decreased chloride (hyperchloremia): Chloride is normally lost in the urine, sweat, and stomach secretions. Excessive loss can occur from heavy sweating, vomiting, and adrenal gland and kidney disease.
The normal serum range for chloride is 98 - 108mmol/L.
Bicarbonate:
The bicarbonate ion acts as a buffer to maintain the normal levels of acidity (pH) in blood and other fluids in the body. Bicarbonate levels are measured to monitor the acidity of the blood and body fluids. The acidity is affected by foods or medications that we ingest and the function of the kidneys and lungs. The chemical notation for bicarbonate on most lab reports is HCO3- or represented as the concentration of carbon dioxide (CO2). The normal serum range for bicarbonate is 22-30 mmol/L.
Question 3. When should I check my electrolyte levels?
The following conditions will warrant electrolyte checks:
Severe diarrhoea not controlled with oral electrolyte replacement
Severe vomiting
Heat cramps
Excessive sweats or nausea not controlled with electrolyte replacement
Leg/ankle swelling
Muscle Cramps or weakness
On medications for diabetes, hypertension, heart or kidney diseases
Bowel obstruction
Any severe infection e.g. pneumonia/meningitis
Kidney Disease
Liver disease
Heart disease
Palpitations
Hypertension
Pancreatitis
Alcohol abuse
Question 4. How is electrolytes Measured?
Measurement of electrolytes is a commonly performed diagnostic procedure, performed via blood testing with ion selective electrodes or urinalysis by medical technologists. The interpretation of these values is somewhat meaningless without analysis of the clinical history and is often impossible without parallel measurement of renal function. Electrolytes measured most often are sodium, potassium, bicarbonate, and chloride levels. This occasionally measured alone with osmolality.
Question 5. Why is it important that I check my electrolytes?
Disturbance in electrolytes can cause major problems. Electrolytes are tightly regulated so that major fluctuations are prevented as disruption of organ functions and nerve signals can occur. For example, problems in sodium levels can cause brain swelling or dehydration and in severe cases patients can become unconscious and stop breathing. Similarly, even minor changes to potassium level can cause life threatening heart rhythm disorders and muscle paralysis. Monitoring of electrolytes are important also for doctors to give correct fluids in very sick patients with add additional electrolytes if required. Some medications are dangerous and cause harm if given in the presence of electrolytes abnormalities.
Question 6. What is the treatment.
Treatment is replacement of lost electrolytes in the form of electrolyte fluids. In some cases of electrolyte abnormality such as from diarrhoea, special electrolyte fluids from chemist e.g. gastrolyte may be adequate. These anti-diarrhoeal fluids are readily available in various brands ready for use in premixed forms throughout pharmacies in PNG. However, it is important to identify specific disorder as treatment differs depending on the abnormality. It can be dangerous replacing electrolytes without knowing specific abnormality.
For example, if you are having cramps due to low potassium you would need immediate potassium replacement rather than giving only electrolyte fluids. In heart failure or severe infections fluid restriction rather than more electrolyte fluids may be required for electrolyte abnormality.
