Hypokalemia is when the body has low potassium levels outside the cell (in the bloodstream). Potassium is an electrolyte that plays a vital role in many bodily functions, particularly in the heart and cardiovascular system. Therefore, it is essential for the proper functioning of the body, and when potassium levels are high or low, this can cause our patients to be very sick and can even cause death.
As a nurse, it’s essential to be aware of the signs and symptoms of hypokalemia and the nursing interventions and low-potassium treatments that can be used to manage this condition. In this article, we’ll explore the symptoms of hypokalemia, nursing interventions that can be used to address low potassium levels, and effective treatment options for patients with this condition.
WHY IS POTASSIUM SO IMPORTANT IN THE BODY
Electrolytes help our bodies perform daily functions and survive. Without potassium or our other electrolytes, we literally couldn’t survive.
Electrolytes are ions with a positive or negative charge, and these help cells create energy, conduct impulses, and do what they need to do. Potassium is positively charged. Some of the functions that potassium helps regulate in the body include:
Potassium is essential for proper muscle function, including both skeletal and smooth muscle. It helps the muscles contract and relaxes, impacting movement, digestion, and much more!
Potassium is essential in regulating fluid balance within the body. Potassium has the same tonicity as sodium, drawing water with it wherever it goes. Potassium is essential in the movement of fluid across cell membranes.
Probably one of potassium’s most essential functions, it helps the cardiac system function! The heart uses conductive tissue, which uses potassium to help transmit its signal for every heartbeat – just like it uses calcium, magnesium, and sodium as well!
Blood Sugar Control
Studies show that high-potassium diets can help improve insulin sensitivity and reduce the risk of type 2 diabetes.
Just like our heart, the nervous system is ALL about conducting electricity and “action potentials,” but on a much more complex level. Potassium helps our nerve cells communicate with each other.
This is a catch-all, but the sodium-potassium pump is essential for the proper function of almost every cell in our body. That’s how vital potassium is and how hypokalemia can affect our patient’s health!
How Is Potassium Regulated In The Body?
The body regulates potassium in many ways to maintain it at the appropriate level to help it maintain homeostasis and function at its optimal capacity. Nurses should be aware of these mechanisms and take proper steps to monitor and maintain healthy potassium levels in their patients, particularly those with conditions that may affect potassium balance, such as kidney disease or heart disease.
Some of the ways the body regulates potassium and prevents hypokalemia include:
The kidneys play a crucial role in regulating potassium levels. These filter out excess potassium and retain more potassium when levels are low.
Several hormones impact potassium levels, primarily Aldosterone and Insulin.
Aldosterone, produced by the adrenal glands, is a signal that tells the kidneys to retain more sodium and potassium.
Insulin, which is produced by the pancreas, helps to promote the uptake of potassium into the cells.
The body’s acidity can also affect potassium levels, with acidosis causing potassium to move out of the cells into the bloodstream and interstitial spaces.
Dietary potassium intake is essential in helping the body maintain adequate potassium levels; however not as important as you might think since the body is good at keeping extra potassium if dietary intake is inadequate.
Potassium levels and Acidotic States
Remember that severely acidotic states, like that in DKA, leave the body with significant decreases in potassium. There is a LACK of insulin, which normally moves potassium into cells, and then there is also acidosis which further shifts potassium out of cells. That’s why it is SO important to replace potassium FIRST before insulin (if low). Read more about DKA here!
Hypokalemia And Normal Potassium Levels
Normal Potassium Levels
- Normal = 3.5 – 5.0 mEq/L
- Mild Hypokalemia: 3.0 – 3.5 mEq/L
- Moderate Hypokalemia: 2.5 – 3.0 mEq/L
- Severe Hypokalemia: < 2.5 mEq/L
The lower the potassium level, the more likely your patient will experience side effects or complications from hypokalemia.
Remember that this is the level of potassium that is OUTSIDE the cells of the body. The actual amount of potassium that is outside the cell normally is very low. The inside of the cell as approximately 120-150mEq/L… That’s 30 times the level from the outside!
This is why conditions that dramatically shift the potassium outside the cells (like DKA) can lead to a massive depletion of potassium. This is also why replacing potassium is SO important in these instances before fixing the acidosis and the hyperglycemia.
Causes Of Hypokalemia:
As we’ve discussed, many factors impact how the body regulates potassium levels, and similarly, there are various causes of hypokalemia. These include:
Certain medications and conditions can shift potassium into the cells, which can cause low potassium levels. This includes Insulin, inhalers like albuterol, and alkalosis.
A common cause of hypokalemia is when it is lost from the GI system. This is usually from either excessive vomiting, diarrhea, or tube drainage.
There isn’t a ton of potassium in the emesis, but excessive vomiting leads to increased potassium wasting in the urine.
This is when potassium is lost in the urine and is often caused by diuretics like LOOP diuretics (Lasix) or increased mineralocorticoid activity (like hyperaldosteronism, crushing’s syndrome, etc.).
Often, this is not the only cause, as the body is pretty good about compensating for inadequate dietary intake.
Nursing Assessment Of Hypokalemia
Symptoms of hypokalemia will vary depending on the patient and how severe the hypokalemia is. Still, the lower it is, the more likely the patient will exhibit symptoms, and the worse they often are.
Some possible symptoms of hypokalemia or low potassium include:
Muscle weakness is one of the most common symptoms of hypokalemia, which can affect the legs, arms, chest muscles, or any muscle in the body. The patient may have trouble walking, taking the stairs, or lifting objects. This usually only occurs if levels drop below 2.5 mEq/L.
Muscle Cramps & Rhabdo
Severe hypokalemia can lead to muscle cramps and even a buildup of myoglobin, leading to rhabdomyolysis. This can be damaging to the kidneys. Hypokalemia also leads to decreased perfusion of the muscles during exercise, which can worsen rhabdo.
A generally non-specific symptom, but patients with low potassium often experience fatigue.
Hypokalemia can cause ileus and constipation and lead to abdominal distention, nausea, and vomiting. The patient may have diarrhea which may contribute to the hypokalemia, but can also have constipation from hypokalemia.
Hypokalemia can cause numbness and tingling in the hands or feet.
Low potassium can cause the kidneys to produce more urine, leading to increased urination.
Shortness of Breath
This is usually only in severe cases with severe muscle fatigue of the respiratory muscles, and the patient may even need to be intubated.
Risk Factors for Hypokalemia
Even still, most patients with low potassium on blood work will not have any specific symptoms. Certain patients have an increased risk for potassium issues. This includes:
- CKD: Chronic kidney disease can lead to the inability to regulate potassium levels efficiently
- Diabetes: Especially with hyperglycemia, osmotic diuresis can occur, which also causes potassium losses.
- GI disorders: Certain GI disorders like chronic diarrhea or vomiting can lead to potassium losses
- Alcoholism: Excessive alcohol intake can lead to decreased potassium intake and increased urinary losses
- Patients on Diuretics: Patients on Diuretics, such as those with hypertension or CHF, are at increased risk of developing hypokalemia.
Medications that Can Cause Hypokalemia
- Diuretics: These increase urinary output and lead to potassium loss in the urine (Furosemide, hydrochlorothiazide, Metalozone, etc.)
- Corticosteroids: These also cause urinary potassium loss and decrease potassium absorption
- Beta-agonists: This shifts potassium into the cells, leading to lower levels outside the cells. It tends to be temporary.
- Insulin: Also shifts potassium into the cells as discussed above.
The physical assessment of a patient with hypokalemia will depend on the severity of the potassium and other factors as well, but most patients will have no specific physical findings.
- HR: May be fast or low depending on cardiac arrhythmias present
- BP: Largely unaffected, but hypokalemia can increase the risk of hypertension
- Respirations: usually normal, but may be decreased in severe cases that cause paralysis
- SPO2: Usually normal unless respiratory failure
- Temp: Normal
- Signs of muscle weakness, such as difficulty walking or moving
- Signs of fatigue or lethargy
- Listen for irregular heart rhythm, which may be caused by ectopy or arrhythmia from the hypokalemia
- Muscle tenderness may be from hypokalemia.
- Edema or ascites, which may indicate underlying kidney or liver failure that can cause hypokalemia
- Abdominal tenderness, which can indicate GI issues that may be leading to hypokalemia
Treatment of Hypokalemia
Treatment of hypokalemia depends on the severity of the hypokalemia and any symptoms or complications present.
When you get your patient’s results back, and they show hypokalemia, especially < 3.0 mEq/L, then follow the following general interventions:
Assess the Patient
Make sure they don’t have any symptoms and are stable, including a recent set of vital signs.
Notify the Provider
Notify the provider of the potassium levels, your assessment, and their cardiac rhythm.
Evaluate if they are on any medications which may lead to hypokalemia, listed above.
Administer treatment as ordered: Administer PO or IV potassium as ordered.
Treatment for Hypokalemia
The treatment of hypokalemia will depend on how severe the level is low and if the patient has any significant symptoms. This will be ordered by the patient’s Provider team. Treatment generally includes:
Address Underlying Causes
Identifying and addressing the underlying causes of hypokalemia is critical before correcting the potassium. The potassium may not be low but has shifted into the cells from something like alkalosis, hypothermia, and certain medications.
Low magnesium can cause potassium wasting in the kidneys. This means the magnesium level should be evaluated in all patients with hypokalemia and replaced first (assuming the patient is stable).
Oral Potassium (PO)
We need to replace potassium, and a large amount of potassium can be absorbed by the GI system. How much is ordered will depend on the severity of the hypokalemia.
- Mild to moderate hypokalemia = 10-20mEq of potassium given 2-4x/day
- severe hypokalemia or severe symptoms = Doses up to 40mEq 3-4x/day in ADDITION to IV potassium
IV Potassium (IV)
You are limited in how fast you can infuse potassium through the IV to prevent arrhythmias and IV site irritation. Rates can be faster in a central line and slower in a peripheral IV line.
- Mild to Moderate hypokalemia: typically not needed, and PO is fine, but if the patient is NPO, then IV can be given. Through a peripheral line, 10mEq “K-riders” are usually ordered, and you can expect the potassium to increase by ~0.1 mEq per K-rider.
- Severe hypokalemia: In extreme cases, can give 20mEq every 2-3 hours
IV Potassium Infusion Rates
Where your potassium is infusing will change how fast you can infuse. While this may vary based on your specific facility protocol, generally, you can infuse in a peripheral line up to 10 mEq/L over 1 hour and in a central line 20 mEq/L over 1 hour.
However, rates of up to 40 mEq/L can be appropriate in critical and code situations. Again, this should be infused into a central line or multiple peripheral IVs.
Monitoring for Hypokalemia
Patients with hypokalemia need good monitoring, especially if they have moderate to severe hypokalemia.
Potassium levels will be redrawn and assessed depending on the severity and what the Provider orders. Generally, mild hypokalemia is often only rechecked on the next lab draw (usually by the following day). Severe hypokalemia being replaced is recommended to be checked every 2-4 hours (usually in the ICU).
As we’ve discussed, low potassium levels can impact cardiac rhythms, and whenever a patient’s getting IV replacement of potassium or magnesium, they should be on a cardiac monitor to monitor for cardiac ectopy or arrhythmias.
Severe hypokalemia can cause respiratory failure, so monitoring their breathing, lung sounds, respiratory rate, and pulse ox is essential.
IV KCL Burns
If you are running IV potassium alone through an IV, this will often burn the patient. Applying ice packs can help, but your best bet is running fluids slowly and piggybacking the IV potassium into the Y site above, diluting the potassium. And, of course, you should have an order for these IV fluids!
Hypokalemia and Cardiac Arrhythmias
Potassium is super important in the proper conduction of cardiac tissue. Remember that each heartbeat involves rapid depolarization (firing) and repolarization of cardiac conductive cells.
Potassium plays a crucial role in maintaining the resting membrane potential and regulating the overall electrical activity of the heart.
The more common arrhythmias associated with hypokalemia include:
- Premature Ventricular contractions (or ventricular premature beats VPBs)
- Ventricular tachycardia (VTACH or VT).
These are induced by early afterdepolarizations and triggered activity, which can be caused by hypokalemia.
Hypokalemia can cause other arrhythmias include PACs, PJCs, AV blocks, and even Afib.
On the ECG, hypokalemia can manifest in a few ways, including:
- ST segment: Often can cause some ST depression
- T wave: T wave flattening is common
- U waves: U waves become more prominent and visible in hypokalemia. Remember, these are seen best in V4-V6.
- QT Interval: Is prolonged with hypokalemia.
The risk of hypokalemic-induced arrhythmias is highest in elderly patients, those with heart disease, and patients on digoxin or antiarrhythmic drugs who are already predisposed to arrhythmias.
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In conclusion, potassium is an essential electrolyte that plays a vital role in many bodily functions, including muscle function, fluid balance, cardiac and nervous systems, blood sugar control, and cellular function.
Nurses must be aware of the signs and symptoms of hypokalemia and the nursing interventions and low-potassium treatments that can be used to manage this condition.
Patients with hypokalemia require careful monitoring, especially with moderate-to-severe hypokalemia, with careful attention to their cardiac rhythm and respiratory function!
Also check out:
UpToDate & Other Database Sources:
- Causes of hypokalemia in adults
- Clinical manifestations and treatment of hypokalemia in adults
- Evaluation of the adult patient with hypokalemia