Hypokalemia and Hyperkalemia- For Nursing Students

by | May 6, 2020 | Fluid and Electrolytes

Disclaimer: This post contains affiliate links, I make a commission if you use any of the affiliate links. For more information, see my disclosures here.

Hypokalemia and Hyperkalemia- For Nursing Students

We are starting off the fluid and electrolyte series with hypokalemia and hyperkalemia!

In my experience as a med-surg nurse, I saw this fluid and electrolyte imbalance much more than any of the others, so in terms of clinical application it is very relevant.

Plus, nursing schools and the NCLEX love to test on fluid and electrolytes, so you need to make sure you understand this information inside and out.

Once you’re done reading through all this information, you can download this cheat sheet version of the information contained in this post.

Hypokalemia & Hyperkalemia

To begin, let us break down the words “hypokalemia” and “hyperkalemia”.

Hypo=low kal=potassium emia= in the blood

Hyper= high kal= potassium emia= in the blood

So, hypokalemia means low potassium in the blood and hyperkalemia means high potassium in the blood.

If we are concerning ourselves with low and high potassium in the blood, then we should probably know what the normal value is for potassium in the blood.

The widely accepted range for potassium in the blood is 3.5-5 mEq/L.

So, if a patient has hypokalemia, then the lab value will be less than 3.5 mEq/L

If a patient has hyperkalemia, then the lab value will be more than 5 mEq/L.

There are some fatal issues that can occur when potassium is not kept within range, and we will be going over those shortly.

First, we should take some time to review the role potassium plays in our body since that is the electrolyte that is in question. This way we can better understand the manifestations that occur when potassium is out of balance.

Potassium

Potassium is regulated mainly by the hormone aldosterone which is secreted by the adrenal glands, which sits right on top of the kidney.

When potassium is high, aldosterone causes more potassium to be excreted in the urine. And when potassium is low, aldosterone secretion is decreased, therefore less potassium is signaled to be excreted in the urine.

As you can likely extrapolate from this information, urine is the main way that potassium is excreted from the body. It accounts for about 90% of potassium excretion, while the remaining amount is excreted in stool and sweat.

Potassium plays a role in maintaining intracellular fluid volume, pH balance, and protein synthesis.

The main function that you should focus on about potassium is its role in excitable cells such as neurons and muscle fibers (smooth, cardiac, and skeletal).

Potassium is an essential element in action potentials (or impulses) in these excitable cells. Therefore, potassium plays a key role in nerve conduction and muscle contractility.

The most simple way to think about this concept is that hypokalemia will cause decreased excitability in excitable cells, whereas hyperkalemia will cause increased excitability in these cells.

Hypokalemia

Here is a video version of all the information to know about hypokalemia if you would like to learn about the information in video form. The causes, signs and symptoms, treatments, and nursing considerations for hypokalemia are reviewed.

Causes:

  • Potassium depleting diuretics such as furosemide. These diuretics cause potassium to be excreted in the urine.  If proper supplementation does not occur, a patient is at high risk of developing hypokalemia.
  • Excess vomiting and diarrhea can cause potassium levels to be depleted if prolonged as the GI tract is one route of potassium excretion.
  • Hyperaldosteronism causes low potassium levels because as we recently reviewed, aldosterone increases the amount of potassium that is excreted in the urine. In hyperaldosteronism there is an abundance of aldosterone which causes an inappropriate amount of potassium to be excreted.
  • Kidney disorders can cause low potassium due to the kidneys’ large involvement in the excretion of potassium.
  • Alkalosis– during alkalosis the potassium that is normally present in the extracellular space is pushed into the cells in exchange for hydrogen ions, thereby decreasing the blood levels of potassium

Signs/symptoms:

Think decreased muscle activity and decreased neuronal activity due to a lack of potassium.

*decreased excitability*

  • Hyporeflexia and generalized weakness- Patients may report that they are not able to tolerate normal activities that they were previously able to do. If you were to test their reflexes you would find that they are diminished or there is no reflex at all. 
  • Decreased respiratory effort- breathing requires the use of muscles, so we see ineffective breathing patterns.
  • Decreased intestinal peristalsis- the smooth muscle in our intestines moves digested materials and stool along. If patients are experiencing decreased peristalsis then they will likely have constipation, which may be accompanied by abdominal pain, nausea, or vomiting.
  • Dysrhythmias- the heart is a muscle therefore we see dysrhythmias in patients who have hypokalemia. You may assess a weak and thready pulse. ECG changes include ST depression, inverted T wave, and a prominuent U wave.
  • Altered mental status- the brain is made of excitable cells (neurons), so patients may experience changes in their cognition. They may be irritable, anxious, or confused.

Treatment:

  • Oral or IV potassium supplementation- this will depend on the severity. If a patient is taking a potassium depleting diuretic and mild hypokalemia, then it may be most appropriate to start them on oral potassium supplements. If a patient is having serious manifestations of hypokalemia and their hypokalemia is severe, then it is likely that IV potassium will be needed.
  • Potassium sparing diuretic- if a patient must be on a diuretic and was previously taking a potassium depleting diuretic, then the potassium depleting diuretic should be discontinued while a potassium sparing diuretic is started. Two common potassium sparing diuretics are spironolactone (Aldactone) and triamterene.

Hyperkalemia

Here is a video version of all the information to know about hyperkalemia if you would like to learn about the information in video form. The causes, signs and symptoms, treatments, and nursing considerations for hyperkalemia are reviewed.

Causes:

  • Potassium sparing diuretics: these diuretics cause the body to hold on to potassium instead of excreting it, so patients who are on these medications are at a high risk of developing hyperkalemia
  • Addison’s disease/adrenal insufficiency- the adrenals secrete several hormones, one of which is aldosterone. If the adrenals are insufficient, then they aren’t secreting an adequate amount of hormones (i.e. aldosterone). If we don’t have enough aldosterone, then our body is unable to signal the action of excreting excess potassium. Hence the development of hyperkalemia.
  • Kidney disease- if our kidneys are not working then we will not be able to excrete potassium in the urine as we normally would. Damaged kidneys are not able to filter at an optimal level, therefore there is a high risk of developing hyperkalemia. Patients who have kidney disease are also at risk of developing hyperkalemia if they continue to eat foods that are high in potassium.
  • Tissue damage, burns– the cells in the tissues that are damaged will die as a result of the trauma. During cell death, potassium is released and enters the bloodstream, therefore increasing blood potassium levels.
  • Acidosis– (this is the opposite of what occurs in hypokalemia) this time, the potassium is moved out of the cells into the extracellular space in exchange for hydrogen ions, thereby increasing the blood level of potassium.

Signs/symptoms

Think increased muscle activity and increased neuronal activity due to an abundance of potassium.

*increased excitability*

  • Muscle twitching- in the early stages of hyperkalemia a patient will likely experience muscle twitching. However, as the hyperkalemia is sustained or worsened, weakness and flaccid paralysis will result.
  • Increased intestinal peristalsis– as we discussed earlier, the smooth muscle of our bowel is an excitable tissue and so it will experience negative effects from an imbalance in potassium. In this case, there is increased intestinal peristalsis so the patient will likely experience diarrhea.
  • Dysrhythmias- as with hypokalemia, the cardiac muscle is affected by an increase in potassium in the blood. Severe hyperkalemia can even lead to cardiac arrest. ECG changes include tall peaked T waves, widened QRS complex, prolonged PR interval.
  • Paresthesia- an abnormal sensation of tingling or numbness

Treatment

  • Kayexalate- this medication excretes potassium through the stool
  • IV insulin + glucose– insulin shifts glucose and potassium into the cells, so it is utilized in hyperkalemia to shift the blood levels of potassium into the intracellular fluid. To prevent hypoglycemia, glucose is also administered.
  • Potassium depleting diuretic- if the kidneys are functioning properly in a patient, then a potassium depleting diuretic may be utilized. These diuretics cause potassium to be excreted in the urine.
  • Dialysis- if the hyperkalemia is severe enough, then dialysis may be initiated to filter out the potassium of the blood.
  • Calcium gluconate– because hyperkalemia can be damaging to the cardiac tissue and severe cardiac manifestations may occur, calcium gluconate is used to negate these effects. It is important to note that calcium gluconate will not lower the potassium levels in the blood. It is used to prevent fatal cardiac arrhythmias

We have reviewed the causes, s/s, and treatments for both hypokalemia and hyperkalemia. Now, let us focus on some of the nursing considerations that are important to take note of.

Nursing Considerations

The cardiac manifestations of both hypokalemia and hyperkalemia can be fatal. It is important to monitor cardiac function closely by ensuring telemetry has been initiated. If a patient is receiving IV potassium, then also be mindful of the potential cardiac alterations that could occur.

IV potassium should never be given IV push. IV potassium will always be an infusion that is diluted and given over a period of time. Administering IVP potassium could cause cardiac arrest and death.  

IV potassium infusions are preferably administered into a central line. Potassium is a severe tissue irritant, so if it is being infused into a peripheral line, the IV insertion site should be assessed frequently. Patients may complain of burning at the IV insertion site during the infusion if being infused into a peripheral line.

Before administering IV potassium ensure the patient has adequate urine output. Do not infuse IV potassium if the patient is not urinating. This could cause severe hyperkalemia.

If a patient is given an oral potassium supplement, then be sure to educate them on the potential development of GI upset. To prevent GI upset from occurring, teach the patient to take their oral potassium during or after a meal.

Educate your patients who have low potassium levels on foods that are high in potassium (spinach, bananas, beans, sweet potatoes, avocados, etc.) Encourage them to eat these foods regularly. In patients who have kidney disease and hyperkalemia, you will want to encourage them to avoid eating these potassium rich foods.

I hope that this information was helpful to you. I tried to put the information into simple terms to avoid complicating an already complicated matter!

If you haven’t already checked out my other posts on the other fluid and electrolyte imbalances, you can click the links below to be taken to each of the individual posts. Each of them have a downloadable cheat sheet so be sure to grab those!

Be sure to also check out my tips on how to study and pass nursing exams in nursing school, so you can pass your fluid and electrolyte exam with flying colors!

As always, if you have any questions please feel free to reach out to me.

Happy Nursing!