Here are eight signs and symptoms of potassium deficiency.
Weakness and fatigue
Weakness and fatigue are often the first signs of potassium deficiency, for a few reasons.
Reading: Symptoms of low potassium levels
First, potassium helps regulate muscle contractions. When blood potassium levels are low, your muscles produce weaker contractions (2).
Second, deficiency in this mineral may affect how your body uses nutrients in a way that can result in fatigue.
For example, some evidence shows that a deficiency could impair insulin production. This can result in high blood sugar levels and less available glucose, which functions as energy for your cells (4).
Since potassium helps regulate muscle contractions, deficiency may result in weaker contractions. A deficiency may impair your body’s handling of nutrients, like sugar, which can lead to fatigue.
Muscle weakness and cramps
Muscle cramps are sudden, uncontrolled contractions of the muscles. They can occur when blood potassium levels are low and can be painful (2).
Within skeletal muscle, potassium helps relay signals from your brain to stimulate contractions. It also helps end these contractions by leaving the muscle cells. When blood potassium levels are low, your brain cannot relay these signals as effectively (2, 8, 9).
This results in more prolonged contractions and is thought to contribute to muscle cramps. Cramps are unlikely to occur with mild or moderate hypokalemia, but they may happen with severe hypokalemia of less than 2.5 mmol/L of potassium (8, 10, 11).
In rare cases, severe hypokalemia can also cause rhabdomyolysis. This is a dangerous medical condition involving the breakdown of muscle tissue that releases damaging protein into the blood, potentially leading to organ damage (11).
In most cases, significant muscle weakness occurs with severe hypokalemia, though it can sometimes occur with acute onset of mild or moderate hypokalemia as well (1).
Potassium helps start and stop muscle contractions. Low blood potassium levels can affect this balance, causing uncontrolled and prolonged contractions known as cramps.
While digestive problems have many causes, they may occur with severe hypokalemia.
Potassium helps relay signals from your brain to muscles located in the digestive system known as smooth muscle. These signals stimulate contractions that help your digestive system churn and propel food, so it can be digested (12, 13).
With low potassium levels, contractions in the digestive system may become weaker and slow the movement of food. This could cause digestive problems, like bloating and constipation.
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In particular, constipation is most associated with severe hypokalemia (2).
Potassium deficiency may cause issues like bloating and constipation because it can slow the movement of food through the digestive system.
Abnormal heart beat
Potassium also plays a vital role in maintaining healthy heart muscle contractions (14, 15).
This is because the flow of potassium in and out of heart cells helps regulate your heartbeat. Low blood potassium levels can alter this flow, resulting in abnormal heart rhythms known as heart arrhythmia (14, 15, 16).
Heart arrhythmias can also be a sign of a serious heart condition. If you notice any abnormal changes to your heart rate, seek immediate medical attention.
Potassium plays a key role in regulating your heart rate. If levels are too low, it may lead to an irregular heartbeat known as heart arrhythmia, which can be a sign of a serious heart condition.
A severe potassium deficiency can cause breathing difficulties.
Breathing requires multiple muscles, especially your diaphragm, to help the lungs inhale and exhale air.
When blood potassium levels are severely low, your lungs may not expand and contract properly, resulting in shortness of breath (17).
Severe potassium deficiency may even stop the lungs from working, which is fatal (18).
One study found that people with low or high blood potassium levels — called hypokalemia and hyperkalemia, respectively — were at significantly higher risk of in-hospital respiratory failure and the need for a ventilator compared with people with healthy potassium levels (18)
Potassium helps the lungs expand and contract, so potassium deficiency may result in shortness of breath.
Tingling and numbness
Though more common in people with high potassium, or hyperkalemia, those with potassium deficiency may also experience persistent tingles and numbness (19).
This is known as paresthesia and usually occurs in the hands, arms, legs, and feet.
Potassium is important for healthy nerve function. Low blood levels can weaken nerve signals and result in tingling and numbness (2).
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While occasionally experiencing these symptoms is harmless — like if your foot falls asleep from lack of movement or sitting in an awkward position — persistent tingles and numbness may be a sign of an underlying condition.
If you experience this, it’s best to contact a doctor.
Persistent tingling and numbness may be a sign of impaired nerve function due to potassium deficiency. If you experience this, it’s best to contact a healthcare professional.
Polyuria (frequent urination)
Polyuria is a condition where you pee more than usual (20).
The kidneys are responsible for balancing your body’s fluid and electrolyte levels and removing any waste through the urine (21).
Low potassium levels may impair your kidneys’ ability to concentrate urine and balance the blood’s electrolyte levels, leading to increased urination. You may also notice increased thirst, known as polydipsia (2, 5).
Excessive urination may lead to lower levels of potassium. Therefore, it’s important to speak with a healthcare professional if you notice a sudden change in how often you urinate.
In some cases, low potassium may impair your kidney’s ability to regulate your body’s fluid and electrolyte balance. As such, you may feel the need to urinate more often.
High blood pressure
Having the perfect balance of electrolytes is important for maintaining healthy blood pressure.
You may be aware that consuming too much sodium can increase blood pressure in some people. Yet, few people know that too little potassium in the diet can have the same effect.
Potassium helps your kidneys get rid of excess sodium via urine. If there isn’t enough potassium in the blood, the kidneys reabsorb sodium back into the bloodstream, potentially leading to high blood pressure over time (22, 23).
This most often occurs with a low dietary intake of potassium — and specifically with hypokalemia (1, 22, 23).
Therefore, getting enough potassium in your diet may be a way to maintain healthy blood pressure in some individuals.
If you have high blood pressure, it’s best to talk with a healthcare professional about monitoring and treatment.
Potassium plays a key role in regulating sodium levels in your body. When your potassium levels are low, your kidneys retain more sodium in the body, which can lead to increased blood pressure.
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