This is a comprehensive review over fluid and electrolytes for nurses. You will learn about the main causes and sign/symptoms of the following electrolytes: Potassium, Sodium, Chloride, Phosphate, Magnesium, and Calcium.
If you would like to learn about these individually along, with their signs and symptoms you can check out this fluid and electrolytes playlist.
Fluid and Electrolytes Nursing Review
We need a proper balance of fluids and electrolytes in our body to maintain life (not too high or too low…just the right amount).
In fact, our body consists of 70% water and below you can see the function of water in our body. However, this water in our body is not just plain water. It consists of so many substances such as electrolytes.
What are electrolytes?
These are substances that once they enter and dissolve in water (hence our blood) they produce an electrical charge (become ions), which helps with electrical signaling in the body and other important processes.
Our body is really “electric” because a lot of the processes it does requires electrical signaling.
For instance, we need a balanced amount of electrolytes for the following functions:
- Contraction of muscles
- Sending nerve impulses
- Creating bones
- Balancing the fluids in our body like our cells (via osmosis)
- Maintaining the blood’s acid-base balance
When certain electrolyte imbalances occur some of the functions above will present abnormally. For example with “contraction of muscles”, if certain imbalances occur muscle spasms can present. In addition, the heart (which is a muscle) can cause an abnormal EKG (which is a test that assesses the electrical activity in the heart).
How does our body balance electrolytes?
We consume these electrolytes through our diet via the foods and drinks we consume. Our kidneys filter and reabsorb what electrolytes we need and don’t need in our body. The kidneys do this via the nephrons in the kidneys, which are the functional parts of the kidney.
Therefore, if a patient is experiencing kidney failure these electrolytes will become imbalanced (many times too high and the patient will need dialysis to help correct the imbalance).
Other ways electrolyte levels can become imbalanced is if they are lost in the body via an exit route. Electrolytes at present in the urine, sweat, emesis, blood, and stool (really any type of body substance). Plus, certain medications can affect electrolyte levels along with trauma like burns or other disease processes.
So, let’s learn about the 6 major electrolytes that make up our body.
What is Sodium?
It’s a very important electrolyte that helps regulate water inside and outside of the cell. And it helps with muscle contraction and transmission of nerve impulses.
Normal levels: 135-145 mEq/L
Sodium mainly hangs out in the OUTSIDE of the cell in fluid and helps water move inside and outside the cell as needed.
So for example, when blood levels of sodium drop in the blood it affects the cells because suddenly water starts to rush into the cell. This causes the cell to swell. On the flip side, when too much sodium is outside the cell, water from inside the cell starts to leave and the cell shrinks.
Low sodium in the blood (less than 135 mEq/L)
- Not consuming enough sodium
- Diuretics “thiazides”
- Vomiting (GI suction…rich in sodium and potassium)
- Low secretion of aldosterone (Addison’s Disease)
- Aldosterone: regulates blood pressure and causes water and sodium to be kept by the kidneys but in turn excretes potassium
- Low amount of aldosterone: would cause the kidneys to not reabsorb much sodium and drop blood levels and in turn would cause the kidneys to keep potassium (leading to hyperkalemia)
- SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion): too much ADH is released causing the body to retain water which dilutes the sodium level.
- Overload of fluid (dilutes sodium) with congestive heart failure, hypotonic fluids infusions, renal failure
- Aldosterone: regulates blood pressure and causes water and sodium to be kept by the kidneys but in turn excretes potassium
Signs and Symptoms of Hyponatremia
Remember “SALT LOSS”
Seizures & Stupor (decrease in consciousness…confusion)
Tendon reflexes diminished, trouble concentrating
Loss of urine & appetite
Orthostatic hypotension, overactive bowel sounds
Shallow respirations (happens late due to skeletal muscle weakness)
Spasms of muscles
High sodium in the blood (greater than 145 mg/dL)
- Cushing’s Syndrome (high cortisol can cause sodium retention and low potassium)
- Primary Hyperaldosteronism (Conn’s Syndrome)
- too much production of aldosterone (retain sodium along with fluid and excrete potassium)
- hypertonic solutions
- Not drinking enough water or losing too much water (vomiting, diarrhea, diabetes insipidus…urinating so much fluid out, sweating, burns)
- increased intake of sodium
Signs and Symptoms of Hypernatremia
Remember: “No FRIED foods for you!” (too much salt)
Restless, really agitated (confused….central nervous system changes)
Increased reflexes (progress to seizures and coma)
Extreme thirst (*big sign)
Decreased urine output, dry mouth/skin
What is Chloride?
Chloride plays a role with acid-base balance in the body along with balancing the fluids in our body by working with sodium to maintain osmotic pressure. Also, sodium and chloride really go together, and if sodium is decreased, chloride is likely to be decreased as well.
Furthermore, chloride is needed to make hydrochloric acid, which plays a huge role in food digestion. The kidneys help maintain chloride blood levels by taking what you don’t need and excreting it in the urine. Chloride is also excreted through sweating and gut juices.
Therefore, if chloride is imbalanced (especially high) it may be a kidney problem because specific parts of the nephron remove chloride from the blood and place it in the urine (if the kidneys aren’t functioning right this can’t happen so more stays in the blood).
Normal level: 95-105 mEq/L
Low chloride levels in the blood ( <95 mEq/L)
- Loss of Chloride: GI system (vomiting, gastric juice loss via NG tube suction or ileostomy)
- Diuretics (thiazides and loop diuretics affect how renal tubules reabsorb sodium and chloride which causes more loss of the ions in the urine)
- Cystic fibrosis (high amounts of chloride in the sweat)
- Metabolic alkalosis (increase in bicarbonate leads to low levels of chloride…they have an opposite relationship due to how each ion shifts in the red blood cells for proper gas exchange)
- Fluid overload (diluting extracellular fluid: CHF, SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion): too much ADH is released causing the body to retain water, which dilutes the sodium level)
Signs and symptoms of hypochloremia tend to be associated with whatever is causing the low level (rather than the level being low itself, so you want to look at what is causing the low level to identify the signs and symptoms) and tends to look like hyponatremia signs and symptoms but you may see:
- Dehydration (increased heart rate, decrease blood pressure, fever)
- Vomiting, diarrhea, lethargic
High chloride in the blood ( >105 mEq/L)
- High intake of sodium (IV fluids…hypertonic fluids or too much saline)
- Not drinking enough water or losing too much water (vomiting, diabetes insipidus: urinating so much fluid, sweating)
- Losing too much bicarb via diarrhea
- Metabolic acidosis (kidney failure or medications that cause it)
- Hyperaldosteronism (Conn’s Syndrome)…too much production of aldosterone (retain sodium along with fluid and excrete potassium)
Signs and Symptoms tend to be associated with whatever is causing the high level (rather than the level being high itself) so you want to look at what is causing the high level to identify the signs and symptoms) and it may look like hypernatremia and acidosis signs and symptoms.
What is Potassium?
It’s an electrolyte that is mainly found in the intracellular part of the cell (inside of the cell) compared to the extracellular (outside of the cell), which is where sodium is mainly found. Sodium and potassium are affected by each other.
Typically, if the sodium levels increase (potassium decreases) and sodium level decreases (potassium increases). Therefore, potassium helps with fluid balance like sodium, especially inside the cell. In addition, potassium is responsible for nerve impulse conduction and muscle contraction.
Normal levels: 3.5-5 mEq/L
Low potassium in the blood (<3.5 mEq/L)
- Medications (diuretics “loop diuretics”, corticosteroids, too much insulin (moves potassium from the blood into the cell which depletes the blood level)
- Cushing’s Syndrome (high cortisol…sodium retention…low potassium)
- Not consuming enough potassium (starvation)
- losing from vomiting, GI suction, sweating
Signs and Symptoms of Hypokalemia:
Try to remember everything is going to be SLOW and LOW. Don’t forget potassium plays a role in muscle and nerve conduction so muscle systems are going to be messed up and affect the heart, GI, renal, and the breathing muscles for the lungs.
7 L’s (Low)
- Lethargy (confusion)
- Low, shallow respirations (due to decreased ability to use accessory muscles for breathing)
- Lethal cardiac dysrhythmias (ST depression, shallow T wave, projecting U wave)
- Lots of urine (frequent urination…kidneys unable to make the urine concentrated)
- Leg cramps
- Limp muscles (decrease deep tendon reflexes)
- Low BP & Heart
High potassium in the blood (>5 mEq/L)
- Cellular movement of potassium from the intracellular to extracellular
- Rhabdomyolysis (break down of muscle tissue which releases potassium from the damaged muscle tissue into the blood)
- Addison’s Disease: low secretion of aldosterone (regulates water and sodium in kidneys by causing the kidneys to reabsorb water and sodium and excrete potassium
- Low amount of aldosterone would cause the kidneys to not reabsorb much sodium but excrete it and reabsorb more potassium and increase blood levels
- Renal failure (unable to excrete potassium and builds up in blood)
- Excessive intake of potassium
- Medications (potassium-sparing diuretics: spironolactone, ACE inhibitors, NSAIDS)
Signs and Symptoms of Hyperkalemia:
Urine output little or none (renal failure)
Respiratory failure (due to muscle weakness)
Decreased cardiac contractility (weak pulse/low HR)
Early: muscle twitches/cramps
Rhythm changes: Tall peaked T-waves, prolonged PR interval (increased higher p-wave not visible)
What is Calcium?
Calcium plays a huge role in bone and teeth health along with muscle contraction/nerve transmission, cell, and blood clotting. Calcium is absorbed in the GI system (so a diet rich in calcium is essential for maintaining calcium blood levels), and it’s stored in the bones. Therefore, if blood levels drop the bones will release some calcium in the blood to help maintain levels, but this can be unhealthy overtime and lead to osteoporosis.
To maintain balanced calcium blood levels, it has to have some help from:
Vitamin D helps play a role in calcium absorption in the GI system. In addition, hormones play a role with maintaining balanced calcium levels like:
Parathyroid hormone (PTH): it’s found in the parathyroid gland
Calcitonin: it’s found in the thyroid gland
Therefore, any problem with these hormones or the structures that produce these hormones can lead to an imbalance of calcium levels.
In addition, phosphorus and calcium affect each other in the opposite way. For instance, if phosphorus levels are high in the blood, calcium will decrease and vice versa. They are always doing the opposite (remember this because it is important for the causes of hypocalcemia).
Normal calcium level: 8.5 to 10.5 mg/dL
Low calcium in the blood (<8.5 mg/dL)
- Low parathyroid hormone (removal or surgery of parathyroid gland or of the neck…thyroidectomy…damages structures that help support calcium levels)
- Low intake of calcium (lactose intolerance)
- low vitamin D intake
- chronic kidney disease (wasting calcium)
- bisphosphonates (help make bones stronger: decreases the release of calcium from the bones into the blood which can lower blood levels of calcium)
- antibiotics…aminoglycosides (“mycin”)…waste calcium by the kidneys
- anticonvulsants (phenobarbital, phenytoin) alters vitamin D levels
Signs and Symptoms of Hypocalcemia
Muscles and nerves will majority be affected “CRAMPS”
Arrhythmias (prolonged QT interval)
Muscle spasms in calves or feet (tetany)
- Trousseau’s and Chvostek’s
- Trousseau’s Sign: You do this by using a blood pressure cuff and place it around the upper arm and inflate it to a pressure greater than the systolic blood pressure and hold it in place for 3 minutes. If it is positive: hand will draw in toward the body and flexion will occur at the wrist, thumb, and MCP (metacarpophalangeal) joints but the fingers remain extended.
- Chvostek’s Signs: shows nerve hyperexcitability of the facial nerve (CN VII)
- To elicit this response you would tap via the masseter muscle at the jaw’s angle and the facial muscles on the same side of the face will contract momentarily (the lips will twitch).
Sensation of tingling and numbness (paresthesia)…fingers/toes
High calcium in the blood (>10.5 mg/dL)
- hyperactive parathyroid (too much calcium released into the blood)
- high intake of vitamin D or calcium supplements
- cancer that has spread to the bones (breaks down the bones which leaks into the blood and increases levels)
- medications: thiazide diuretics, lithium (affects parathyroid and increase levels)
Signs and Symptoms:
Weakness of muscles (profound)
EKG changes shortened QT interval
Absent reflexes (decreased), altered mental status, abdominal distention from constipation
Kidney Stone formation
What is Magnesium?
Magnesium is another major ion found inside the cell just like potassium. Magnesium plays a big role with muscle and nerve function.
For example, it plays a big role with how ATP works with the sodium-potassium pump. Magnesium helps by binding with ATP (which needs mag ions to function) so 3 sodium ions can move out of the cell and 2 potassium ions can move in the cell…without proper mag levels this function fails to work properly.
Also, mag helps with muscle relaxation. Calcium and mag are competitors in muscle contraction. In a nutshell, calcium plays a vital role in muscle contraction, and magnesium challenges the binding spot of calcium to cause muscles to relax. Therefore, without enough magnesium to calm muscle contractions down, cramping and spasms may occur.
Plus, magnesium is vital for how nerves transmit signals, how our vessels work to maintain blood pressure, and how the heart muscle contracts.
Magnesium is absorbed in the gut, specifically the small intestine (keep this in mind…because if there is a problem with the small intestine, magnesium absorption can be affected). In addition, it’s excreted through the kidneys.
When magnesium levels are imbalanced, many times other electrolytes imbalances will occur as well (specifically potassium and calcium levels).
Normal magnesium level: 1.5-2.5 mg/dL
Low magnesium level in the blood: (< 1.5 mg/dL)
- Not consuming enough magnesium
- Other electrolyte imbalances presenting
- Wasting magnesium via the kidneys (diuretics)
- Malabsorption by the small intestine or usage of PPIs “proton pump inhibitors”
- Alcoholism, bowel disorders etc.
Signs and Symptoms of Hypomagnesemia
When magnesium is too low to calm things down, excitability will be occurring (opposite for hypermagnesemia).
Trouesseau’s Sign & Chvostek’s Sign (positive due to hypocalcemia)
Increased deep tendon reflexes
Torsade’s de pointes (abnormal heart rhythm that leads to sudden cardiac death…seen in alcoholism) Tetany (seizures) and other EKG changes that go along with calcium and potassium decrease
Calcium and potassium levels low (presents together)
High magnesium level: > 2.5 mg/dL
- Not very common…but can happen when trying to correct hypomagnesemia (too much given)
- Labor and delivery patients receiving magnesium sulfate for treatment of preeclampsia (assessing reflexes…don’t want them decreased or absent…means too much mag)
- Kidney function is impaired because the kidneys are responsible for excreting magnesium
Signs and Symptoms of Hypermagnesemia
Every system of the body is “Lethargic” (opposite of hypomagnesemia where the body systems are experiencing hyperexcitability)
Note: You will typically only see symptoms in severe cases of hypermagnesemia (mild cases the patient may be asymptomatic)
EKG changes with prolonged PR & QT interval and widened QRS complex
Tendon reflexes absent/grossly diminished
Arrhythmias (bradycardia, heart blocks)
Red and hot face (flushing)
GI issues (nausea, vomiting)
Impaired breathing (due to skeletal weakness)
Confusion (neuro impairment)
What is phosphate?
Normal phosphate level: 2.5-4.5 mg/dL
Phosphate helps build bones/teeth and plays a role in nerve/muscle function. Majority of the phosphate is stored in the bones. Therefore, it plays a vital role in bone and teeth health. It’s absorbed through food we eat and is excreted through the kidneys (if there is a renal insufficiency, phosphate levels can be high because the kidneys are failing to excrete it).
Also, the parathyroid gland plays a role in the regulation phosphate just like it did with calcium.
It’s important to remember that calcium and phosphate can many times influence each other in opposite ways. For example, when calcium levels increase, in turn phosphate levels decrease (vice versa).
Vitamin D plays an important role in phosphate absorption as well.
Low phosphate level in the blood (<2.5 mg/dL)
- Long-term usage of aluminum-based antacids (blocks the absorption of phosphate by the intestines)
- Starvation or refeeding syndrome
- This happens when food is reintroduced after the body has been in starvation mode (hence the body went into survival mode and is depleted of almost everything). When nutrition is introduced, the body releases insulin due to the increased blood sugar from the food, which causes the body to rapidly use the already low stores of phosphate. Phosphate is needed by the body’s cells to change glucose into energy. This process further depletes phosphate levels).
- Overactive parathyroid gland (parathyroid plays a role in maintaining calcium and phosphate levels and it normally inhibits reabsorption of phosphate by the kidneys)
- Low vitamin D intake
- Severe burns (moves phosphate intracellularly)
- Alcoholism (malabsorption and poor diet)
Signs and Symptoms of Hypophosphatemia
Typically seen when the levels are severely low (not mildly)
Bone pain and fractures
Osteomalacia (softening of bones) results in bowing of the legs…affect growth in children (shorter)
Neuro status changes (irritability, confusion, seizures)
Erythrocyte destruction (red cells destroyed leading to hemolytic anemia)
High phosphate level in the blood (>4.5 mg/dL)
- Over usage of phosphate containing laxatives (fleets enema)
- Over usage of vitamin D supplements
- Rhabdomyolysis: break down of muscle occurs and myoglobin enters bloodstream and causes kidney failure…leading to the inability to excrete phosphate)
- Hypoparathyroidism (normally PTH inhibits the reabsorption of phosphate, but when underactive it cause phosphate to be absorbed by the kidneys)
Signs and Symptoms of Hyperphosphatemia
Hypocalcemia will be seen
Muscle spasms in calves or feet, tetany, seizures
Pruritus* (itching…found in many patient with renal failure)
Signs of Chvostek and Trousseau’s