Hyperkalemia

Original Editors -Courtney Ahlers & Jessica Ketterer from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Jessica Ketterer, Lucinda hampton, Elaine Lonnemann, Admin, Kim Jackson, WikiSysop, 127.0.0.1, Wendy Walker and Aminat Abolade  

Definition/Description

Potassium is an important nutrient and electrolyte, it helps muscles work, including those involved in breathing and keeping the heart beating. But too much potassium in our system, known as hyperkalemia, can cause serious health problems. And people with kidney disease are more prone to developing hyperkalemia.

Hyperkalemia is defined as a serum or plasma potassium level above the upper limits of normal, usually greater than 5.0 mEq/L to 5.5 mEq/L. While mild hyperkalemia is usually asymptomatic, high levels of potassium may cause life-threatening cardiac arrhythmias, muscle weakness or paralysis. Symptoms usually develop at levels higher levels, 6.5 mEq/L to 7 mEq/

Image 1: Illustration of the way that differences in ion concentration on opposite sides of a cell membrane produce a voltage difference. Potassium is usually an intracellular cation.

For patients with mild transient hyperkalemia, the prognosis is excellent if the inciting cause is addressed and treated. Sudden onset, extreme hyperkalemia can cause cardiac arrhythmias that can be lethal in up to two-thirds of cases if not rapidly treated. Hyperkalemia is an independent risk factor for death in hospitalized patients.

Etiology

Often a report of high blood potassium isn't true hyperkalemia. Instead, it may be caused by the rupture of blood cells in the blood sample during or shortly after the blood draw. The ruptured cells leak their potassium into the sample. This falsely raises the amount of potassium in the blood sample, even though the potassium level in your body is actually normal. When this is suspected, a repeat blood sample is done.

The most common cause of genuinely hyperkalemia is related to the kidneys, eg:

• Acute kidney failure
• Chronic kidney disease

Other causes of hyperkalemia include:

• Addison's disease (adrenal insufficiency)
• Angiotensin II receptor blockers
• Angiotensin-converting enzyme (ACE) inhibitors
• Beta blockers
• Dehydration
• Destruction of red blood cells due to severe injury or burns
• Excessive use of potassium supplements
• Type 1 diabetes

Image 2: Dialysis for Chronic Kidney Disease.

Epidemiology

Hyperkalemia is unusual in the general population, reported in less than 5% of the population, worldwide.

• Affects up to 10% of all hospitalized patients, most cases in hospitalized patients are due to medications and renal insufficiency.
• Diabetes, malignancy, extremes of age, and acidosis are other important causes in inpatients.
• Hyperkalemia is rare in children but may occur in up to 50% of premature infants.
• Hyperkalemia is more commonly reported in men than women perhaps due to increased muscle mass and higher rates of rhabdomyolysis and increased prevalence of neuromuscular disease.

Today there is a risk that empirical use of ACE inhibitors may cause hyperkalemia, which can be of concern in high risk populations eg diabetics, those with heart failure, and peripheral vascular disease.

Characteristics/Clinical Presentation

Hyperkalemia most commonly occurs in patients with chronic renal failure and is also correlated with diabetes.  

Image 3: ECG is monitored in patients with hyperkalemia:

Signs and Symptoms

1. muscular weakness
2. flaccid paralysis
3. ileus
4. ECG changes
5. nausea
6. slow, weak or irregular pulse
7. sudden collapse (heart rate too slow or stops)
8. paraestesias
9. fatigue
10. palpitations

Potassium is regulated through excretion via the renal system. When this system's function declines, the extracellular potassium concentration increases and can lead to membrane excitability.  Some signs and symptoms listed above are a result of the impaired nerve conduction and muscle contraction dysfunction.  Muscular dysfunction includes the cardiac system and can lead to life threatening ventricular arrhythmias.  Electrocardiogram (ECG) dysfunction is more common in patients with acute hyperkalemia.

Diagnostic Tests/Lab Tests/Lab Values

Initial diagnosis is initiated with patient history, medication review, and physical examination. 

Laboratory tests include:

1. serum electrolytes (especially potassium and glucose )
2. creatinine
3. blood urea nitrogen (BUN)
4. spot urine test (potassium, creatinine, and osmoles)
5. transtubular potassium gradient (assessment of renal potassium handling)
6. trial of oral fludrocortisone (Florinef)

Patients will likely not present with symptoms of hyperkalemia until potassium levels have exceeded 7 mmol/L.  However, immediate medical attention is required when potassium level exceed 6.5 mmol/L or exceed 6.0 mmol/L with ECG changes consistent with hyperkalemia.

  Systemic Involvement  

Table 5-10 Clinical Features of Various Electrolyte Imbalances

Potassium Imbalance (hyperkalemia)	System Dysfunction
Cardiovascular	tachycardia and later bradycardia, ECG changes, cardiac arrest (with levels .7.0 mEq/L)
GI	nausea, diarrhea, abdominal cramps
Musculoskeletal	muscle weakness, flaccid paralysis
Genitourinary	oliguria, anuria
Central nervous system	areflexia progressing to weakness, numbness, tingling, and flaccid paralysis
Acid-base balance	metabolic acidosis

Treatment

The urgency with which hyperkalemia should be managed depends on how rapidly the condition developed, the absolute serum potassium level, the degree of symptoms, and the cause.

• The presence of ECG changes, a rapid rise of serum potassium, indications of decreased kidney function, or significant acidosis require immediate medical treatment for hyperkalemia. 
• Although ECG changes are common indicators for severe hyperkalemia, the patient may still have life threatening hyperkalemia even if ECG readings are normal. 
• The intent of immediate medical intervention is to stabilize the myocardium to prevent arrhythmias. 

In addition to the medications listed in Table 5, total body potassium levels can be lowered through kidney excretion, gastrointestinal (GI) elimination, or dialysis.  Lowering via kidney excretion is achieved by the use of diuretics, while lowering via GI elimination occurs with the use of Kayexalate.  Long term management is focused on addressing the underlying cause, which can be achieved by discontinuing medications or consuming low potassium diets.

Figure 2:  Algorithm for the management of hyperkalemia.

Foods high in potassium can also be implicated in the development of hyperkalemia. 

Table 2. High-potassium foods (National Kidney foundation, 2010)

- salt substitutes and salt free broth - yogurt, milk - molasses - seaweed - chocolate - bran cereal, wheat germ, granola - vegetables (acorn squash, artichoke, bamboo shoots, beets, broccoli, brussel sprouts, chinese cabbage, carrots, greens (except kale), kohlrabi, mushrooms (canned), parsnips, potatoes, pumpkin, rutabagas, spinach, tomatoes, vegetable juices) - dried fruit (apricot, dates, figs, raisins, prunes) - nuts and seeds, (peanut butter) - dried peas and beans (lima beans, black beans, refried beans, lentils, legumes) - fruit and juice (apricot, avocado, banana, cantaloupe, grapefruit, honeydew, kiwi fruit, mango, nectarine, orange, papaya, pomegranate, prune)

Physical Therapy Management

Hyperkalemia is a disorder that is not managed primarily by a physical therapist, however physical therapists should be aware of signs and symptoms of this disorder and should refer the patient to a medical doctor when indicated.

• Potassium levels < 3.2 mEq/L or > 5.1 mEq/L are contraindicated for physical therapy intervention due to the potential for arrhythmia and tetany. 
• When potassium levels are not within the normal range (3.5-5.0 mEq/L) exercise is not effective due to decreased muscle pH and action potentials as well as inhibition of motor neurons. 
• With a patient who has marginal potassium levels, vital signs (including pulse rhythm) and any signs of dizziness, muscle weakness or cramping, numbness or tingling, and changes in balance should be closely monitored. 

At this time, no research addresses the change in potassium level that occurs with exercise.  However, it is known that patients with hyperkalemia are at risk for ventricular arrhythmias which can result in reduced exercise tolerance.

References

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