Fundamentals - Practice & Skills, part 16: Electrolytes and Electrolyte Imbalances

by Meris Shuwarger BSN, RN, CEN, TCRN August 06, 2021 Updated: August 09, 2023 4 min read 1 Comment

This article covers electrolytes and electrolyte imbalances. You can follow along with our Fundamentals of Nursing flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.

Additionally, the Med-Surg Nursing video series, which follows our Medical-Surgical Nursing Flashcards, offers an in-depth look at electrolytes and acid-base balance.

Calcium (Ca)

Calcium is critical for many body functions, including bone and teeth formation, muscle and nerve function, and blood clotting.

The normal range for calcium is 9 to 10.5 mEq/liter.


Hypercalcemia is having too much calcium, which is anything over 10.5 mEq/L.

The causes of hypercalcemia include hyperparathyroidism, prolonged immobility, long-term corticosteroid use, and bone cancer.

The signs and symptoms of hypercalcemia include constipation, a decrease in deep tendon reflexes (DTRs), kidney stones, and lethargy.


Hypocalcemia is having too little calcium, which is anything under 9 mEq/L.

Hypocalcemia may be caused by hypoparathyroidism, as well as decreased Vitamin D intake and diarrhea.

The signs and symptoms of hypocalcemia include positive Chvostek’s and Trousseau’s signs, muscle spasms, numbness and/or tingling in the lips and/or the fingers, as well as GI upset.

A positive Chvostek’s sign is an abnormal reaction to the stimulation of the facial nerve — when you tap on the cheek the muscle twitches.

A positive Trousseau’s sign is an abnormal reaction of the hand to pressure on the arm, for example when a blood pressure cuff is wrapped around it.

For a more in-depth look at medications and supplements that are used to treat and prevent electrolyte imbalances due to calcium, our Lab Values Study Guide & Flashcard Index is a list of lab values covered in our Lab Values Flashcards for nursing students and can be used as an easy reference guide.

Magnesium (Mg)

Magnesium is critical for muscle and nerve function, as well as aiding biochemical reactions in the body.

Magnesium has a normal range of 1.3 to 2.1 mEq/L.


Hypermagnesemia is having too much magnesium, which is anything over 2.1 mEq/L.

The causes of hypermagnesemia include kidney disease, as well as ingesting laxatives and antacids that contain magnesium.

Signs and symptoms of hypermagnesemia include hypotension (low blood pressure), lethargy, muscle weakness, and respiratory and cardiac arrest. It also may lead to a decrease in deep tendon reflexes (DTRs).


Hypomagnesemia is having too little magnesium, which is anything under 1.3 mEq/L.

The causes of hypomagnesemia include GI losses, diuretics, malnutrition, and alcohol abuse.

Signs and symptoms include dysrhythmias (irregular heartbeat (irregular/non-regular rhythm)), tachycardia, hypertension, tremors, and an increase in DTRs (the opposite of hypermagnesemia). Hypomagnesemia also puts the patient at the risk for seizures.

For a more in-depth look at medications and supplements that are used to treat and prevent electrolyte imbalances due to magnesium, our Lab Values Study Guide & Flashcard Index is a list of lab values covered in our Lab Values Flashcards for nursing students and can be used as an easy reference guide.

Potassium (K)

Potassium, critical for nerve function and the regulating of muscle and heart contractions, is a crucial lab value to know.

The normal range for potassium is 3.5 to 5 mEq/L.

An imbalance in potassium could lead to a cardiac arrest.

Cool Chicken K is for "K"ardiac; assess cardiovascular status!


Hyperkalemia is having too much potassium, which is anything over 5 mEq/L.

The causes of hyperkalemia include diabetic ketoacidosis (DKA; also known as hyperglycemia), metabolic acidosis, the ingestion of salt substitutes, and kidney failure.

Signs and symptoms of hyperkalemia include dysrhythmias, muscle twitching and/or weakness, numbness and/or tingling, diarrhea, and confusion.


Hypokalemia is having too little potassium in the body, which is anything under 3.5 mEq/L.

The causes of hypokalemia include the use of diuretics (e.g., furosemide), as well as vomiting, diarrhea, diaphoresis (excessive sweating), and metabolic alkalosis.

Signs and symptoms of hypokalemia include dysrhythmias, muscle weakness, constipation and/or ileus (when the whole GI system peristalsis stops, or is “paralyzed”), hypotension, and a weak pulse.

For a more in-depth look at medications and supplements that are used to treat and prevent electrolyte imbalances due to potassium, our Lab Values Study Guide & Flashcard Index is a list of lab values covered in our Lab Values Flashcards for nursing students and can be used as an easy reference guide.

Sodium (Na)

Sodium maintains the body’s fluid balance and is critical for nerve and muscle functions.

Like potassium, sodium is a vitally important lab value to know. It's normal range is 136 to 145 mEq/L.

A fluid imbalance due to sodium could cause a neurological issue, which is why it is important to assess a patient’s neurological status if they have a sodium imbalance.

Cool Chicken Na is for Neurological; assess for changes!


Hypernatremia is having too much sodium, which is anything above 145 mEq/L.

The causes of hypernatremia include kidney failure, excess sodium intake, fever, and NPO (fasting).

Signs and symptoms of hypernatremia include muscle twitching and/or weakness, thirst, tachycardia, GI upset, edema (excess fluid), irritability or agitation, and coma.


Hyponatremia is having too little sodium, which is anything below 136 mEq/L.

The causes of hyponatremia include diuretics, kidney failure, diaphoresis, hyperglycemia (also known as DKA, mentioned above), heart failure, and fluid volume overload (dilutional hyponatremia).

Signs and symptoms of hyponatremia include confusion, altered mental status, tachycardia, hypotension, weak pulse, fatigue, nausea, vomiting, headache, and seizure.

For a more in-depth look at medications and supplements that are used to treat and prevent electrolyte imbalances due to sodium, our Lab Values Study Guide & Flashcard Index is a list of lab values covered in our Lab Values Flashcards for nursing students and can be used as an easy reference guide.

Full Transcript

Hi. I'm Meris, and in this video, I'm going to be talking to you about electrolytes and electrolyte imbalances. I'm going to be following along with our Fundamentals of Nursing flashcards. These are available on our website If you already have a set and you want to follow along with me, I'm starting on card number 95. Let's get started.

Okay. So first up, we're going to be talking about calcium, which is very important for a lot of body functions. I want to point out to you here on this card, we have a lot of red and bold text, which you're going to see on all the electrolyte cards. This means that this is incredibly important information for you to know for your nursing school exams and for the NCLEX, along with clinical practice. So the normal range for calcium is going to be 9 to 10.5 mEq/liter. Very important to know that. Hypercalcemia is anything over 10.5. Hypocalcemia is anything under the 9. So a couple of things I want to point out. I'm not going to go into too much detail. But one of the causes of hypercalcemia, too much calcium, is prolonged immobility or hyperparathyroidism. Now, when we talk about hypocalcemia, hypoparathyroidism is one of the causes, along with decreased Vitamin D intake and diarrhea. But what I want to point out to you here for hypocalcemia is that two of the findings are bold and red. It's going to be positive Chvostek's and Trousseau's signs. So Chvostek's is tapping on the cheek and seeing the muscle twitch. Trousseau's is having the blood pressure cuff on the arm and seeing the arm kind of go into spasm and tetany. Very important to know these for your nursing exams. I would encourage you, as well, if you don't already have our lab values deck, this would be a great time to get that lab values deck because it covers the normal ranges of all of the labs, along with a lot of other considerations, why tests are run, and so forth. All right. Let's move on.

Next up, we're going to talk about magnesium. So you can see here on the card that our normal range is 1.3 to 2.1 mEq/liter. Anything less than 1.3 is going to be hypomagnesemia. Anything greater than 2.1 is hypermagnesemia. One of the biggest things that I want to point out to you here is the deep tendon reflexes. When you have hypermagnesemia, too much magnesium, you're going to have decreased deep tendon reflexes. If I have too little magnesium, hypomagnesemia, then I'm going to have increased deep tendon reflexes, and I'm also at risk for seizures. So definitely pay attention to the inverse relationship there between magnesium levels and deep tendon reflexes.

Okay. Now we're moving on to potassium. Now, potassium is one of these lab values that I'm going to say you need to highlight it, star it, underline, know everything about it. Normal range is going to be 3.5 to 5 mEq/liter. Anything less than 3.5 is hypokalemia. Anything above 5 is going to be hyperkalemia. Now, why is potassium so important? Potassium helps to regulate muscle function. What is one of the most important muscles in our body? Hint: it's your heart. Sorry. That's not a hint. That's a spoiler. But it's your heart. So when you think potassium, you need to think of the heart. And we actually even have a cool chicken hint right here, which I think is awesome. Potassium, the symbol for potassium is K, so our hint here is K is for cardiac. It helps you to remember to assess the cardiovascular status. So big, big things here are going to be that any time that we have a patient who has a potassium imbalance, we need to be thinking about their heart, looking at their heart, and seeing about any abnormalities in their cardiovascular function.

All right. Let's move on to sodium. Sodium, again, is one of these lab values, one of these electrolytes that is very important and you need to know everything about. So normal range for sodium is going to be 136 to 145 mEq/liter. Anything less than 136 is hyponatremia. Anything above 145 is hypernatremia, too much sodium. Now, we have another really, really great cool chicken hint here which is N, you know Na - so sodium's symbol is Na - so Na is for neurological. So you need to be assessing the neurological status of anybody who has a sodium imbalance. Sodium has a lot to do with regulating the water and fluid balance in our bodies, so any disruption in that can cause changes to our fluid balance. The situation, though, presents when we have a significant disruption in that fluid balance is going to affect the fluid balance within our brains as well. So you need to be thinking about neurological status, and you'll see here that we even have on hyponatremia, bold and red, seizures. Seizures are possible, so you should be thinking, "Maybe my patient should be on seizure precautions." Okay. So that is it for electrolytes and electrolyte imbalances. Very important. And like I said, I would really recommend getting our lab values deck. I think that's going to help you a lot. And when you get to med-surg, and you get much more in-depth with these fluids and electrolytes and acid-base balance, I would say you should definitely get the med-surg deck as well.

If you like this review, thought it was helpful, I would love it if you could like this video. Be sure to leave me a comment if you can think of a better way to remember something. I absolutely want to hear it. And you definitely want to subscribe to the channel because you want to be the first to know when our next video drops. The next one in this series is going to be talking about acid-base imbalances, which is a really important concept for Fundamentals and the rest of your program. So thanks so much, and happy studying.

1 Response


March 29, 2022

bravo!!!educational and helps me with my Adaptive processes H-371:) I would like you to talk about acidosis and alkalosis symptoms for Respiratory and Metabolic. We had the test and I did not study that part like the exam symptoms were given and asked but no ABGs ranges then name based on the symptoms if its resp acidosis or metabolic alkalosis.

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