Signs and Symptoms of Hyperkalemia

Without potassium, we could not live. The electrolyte is responsible for a number of essential life functions. Not only is potassium responsible for regulating water balance in the body, it keeps the heart pumping, the muscles contracting, the gut digesting, and your nerves firing.

That said, too much of a good thing can be harmful. High potassium, medically known as hyperkalemia, is a common laboratory finding. The diagnosis is made when levels in the blood are greater than 5.0 mEq/L. Interestingly, most people do not get any symptoms from it. When they do, those symptoms are often mild and nonspecific, including common complaints like fatigue and generalized weakness.

Most people do not experience more concerning symptoms until their potassium level reaches 7.0 mEq/L or more. However, symptoms can occur at lower levels if the potassium level rises abruptly. Keep an eye out for these symptoms.

Normally, there is more potassium inside and more sodium outside of any given cell. This gradient of electrolytes helps to drive the sodium-potassium ATPase pump that is needed to set off an action potential. Without an action potential, a nerve cannot generate an impulse.

Too much potassium outside of a cell changes the electrolyte gradient so that an action potential is slower to trigger and, in the worst case scenario, may not occur at all.

When it comes to the nerves, this can affect how quickly your reflexes respond or even how well your sensory nerve endings work.

Given this, common neurologic symptoms of hyperkalemia can include:

• Decreased reflexes
• Tingling
• Numbness (rare)

Nerves, in turn, can then stimulate muscle fibers—cardiac, skeletal, or smooth—to contract. If potassium affects action potentials, it by default affects muscle function too.

Skeletal muscles, also called striated muscles, are the muscles that are attached to your bones. They allow you to move your arms and legs and other parts of your body. A muscle that does not receive nerve impulses could have a difficult time contracting or could become weak.

Musculoskeletal symptoms of hyperkalemia can include:

• Muscle weakness
• Paralysis (rare)

Hyperkalemic familial periodic paralysis is an inherited medical condition that puts people at higher risk for these sorts of symptoms. However, the condition is rare, affecting only 1 in every 200,000 people.

Smooth muscle lines the GI tract and is necessary to propel food from your esophagus all the way through the colon in a process known as peristalsis. When potassium levels are high, smooth muscle contractions may be too weak to coordinate that forward movement through the GI tract. This can lead to nausea, vomiting, and the build-up of abdominal gas.

Gastrointestinal symptoms of hyperkalemia can include:

• Abdominal gas and bloating
• Nausea
• Diarrhea
• Vomiting (rare)

The heart conducts signals between cells called myocytes. Action potentials are needed to send the automatic impulses to the myocytes that keep your heart beating.

When blood levels of potassium are too high, contractions of the heart may not be forceful enough to pump enough blood out of the heart to the brain and other organs. The heart rate can also slow down from the delayed firing of action potentials.

In that way, abnormal heart rhythms can also develop. Depending on the arrhythmia, this could be a life-threatening situation.

Cardiac symptoms of hyperkalemia can include:

• Slow heart rate
• Palpitations and cardiac arrhythmia
• Chest pain
• Cardiac arrest (rare) 

Remember that most people do not develop symptoms until their potassium level is above 7.0 mEq/L. If you develop any of the symptoms above, especially across different body systems, you could have very high levels of potassium.

You are encouraged to be proactive and contact your doctor for an evaluation. Most of the time hyperkalemia is found incidentally on blood work. In that case, your doctor is likely to repeat your labs and follow-up with any necessary testing.