We cannot survive without potassium. Electrolytes are responsible for many basic life functions. Potassium is not only responsible for regulating water balance in the body, it also keeps the heart beating, muscle contractions, gut digestion, and nerve activation.
That said, too much of a good thing can be harmful. High potassium, medically known as hyperkalemia, is a common laboratory finding. Diagnosis is made when levels in the blood are greater than 5.5 mEq/L. Interestingly, most people don’t experience any symptoms from it. When they do, the symptoms are usually mild and nonspecific and include common complaints such as fatigue and general weakness.
Most people experience no more worrisome symptoms until potassium levels reach 7.0 mEq/L or higher. However, if potassium levels suddenly rise, symptoms may appear at lower levels. Watch for these symptoms.
Generally, any given cell has more potassium inside and more sodium outside. This electrolyte gradient helps drive the sodium-potassium ATPase pump required to initiate action potentials. Without action potentials, nerves cannot generate impulses.
Too much extracellular potassium can alter the electrolyte gradient so that action potentials fire more slowly and, in the worst case, may not happen at all.
Given this, common neurological symptoms of hyperkalemia may include:
- weakened reflexes
- numbness (rare)
The nerves, in turn, can stimulate muscle fibers—heart, bone, or smooth muscle fibers—to contract. If potassium affects action potentials, by default it also affects muscle function.
Skeletal muscles, also known as striated muscles, are muscles that attach to bones. They allow you to move your arms and legs and other parts of your body. Muscles that are not receiving nerve impulses may have difficulty contracting or become weak.
Musculoskeletal symptoms of hyperkalemia include:
- muscle weakness
- Paralysis (rare)
Smooth muscle lines the gastrointestinal tract and is necessary to propel food from the esophagus all the way through the colon in a process called peristalsis. When potassium levels are high, smooth muscle contractions may be too weak to coordinate forward movement through the gastrointestinal tract. This can cause nausea, vomiting, and gas in the abdomen.
Gastrointestinal symptoms of hyperkalemia include:
- Bloating and bloating
- vomiting (rare)
The heart conducts signals between cells called muscle cells. Action potentials are needed to send automatic pulses to the muscle cells that keep the heart beating.
When potassium levels in the blood are too high, the heart may not contract enough to pump enough blood from the heart to the brain and other organs. Heart rate is also slowed by delayed firing of action potentials.
In this way, abnormal heart rhythms can also occur. Depending on the arrhythmia, this can be life-threatening.
Cardiac symptoms of hyperkalemia may include:
- slow heart rate
- Palpitations and Arrhythmias
- chest pain
- cardiac arrest (rare)
When to see a healthcare provider
Keep in mind that most people don’t experience symptoms until potassium levels are above 7.0 mEq/L. If you experience any of the above symptoms, especially in different body systems, your potassium levels may be very high.
We encourage you to proactively contact your healthcare provider for an evaluation. Most of the time hyperkalemia is discovered incidentally on blood tests. In this case, your healthcare provider may repeat your lab and follow up with any necessary tests.
Frequently Asked Questions
How are the symptoms of hyperkalemia and hypokalemia different?
Hypokalemia (low potassium) has many of the same symptoms as hyperkalemia, including numbness and tingling, palpitations, and shortness of breath. Arguably the biggest difference is the development of muscle spasms and twitches, which are more common in hypokalemia. In the end, the only way to diagnose both conditions is with blood and urine tests.
What are the symptoms of severe hyperkalemia?
Symptoms of severe hyperkalemia may include chest pain, vomiting, weakness, breathing problems, cardiac arrest, paralysis, and palpitations. The presence of any of these symptoms should warrant immediate consultation with a medical professional or your healthcare provider.
How does hyperkalemia cause heart symptoms?
Potassium and sodium regulate electrical signals in the heart muscle, called the myocardium. When potassium levels are too high (or too low), it can interfere with electrical signals and cause arrhythmias (irregular heartbeats) or palpitations (beats).
Causes and Risk Factors of Hyperkalemia