Why the Relationship Between Potassium and Sodium Matters

Sodium and potassium are electrolytes that are required for human survival — having the right balance of these and other electrolytes helps your body maintain normal functions. If you have an imbalance of electrolytes, problems can ensue with how your body operates.

Electrolytes are minerals in your blood that control the distribution of fluids throughout the body, among other functions, according to the Cleveland Clinic.

Major electrolytes your body requires are sodium, potassium, chloride, magnesium, and calcium, according to ​StatPearls​.

Sodium helps keep the body's fluids in balance, while potassium helps with muscle contractions and nerve transmission, according to the National Institutes of Health (NIH). That's why people sometimes recommend having a banana — a high-potassium food — if you're experiencing muscle cramps.

Potassium and sodium have an inverse relationship: As sodium goes up, potassium levels decrease, and vice versa, according to the University of Michigan Health.

When you sweat, you lose electrolytes. Diet, certain medications, hormone levels and other factors can lead to an electrolyte imbalance, per the University of Michigan Health.

And drinking water won't replace electrolytes, according to the NIH.

If sodium levels dip too low, hyponatremia occurs, which causes an array of symptoms from vomiting to seizures, and can potentially be life threatening, according to the Mayo Clinic.

Hyponatremia is rare, per the Harvard T.H. Chan School of Public Health.

When the reverse happens — and sodium levels are too high — it leads to hypernatremia, according to the Merck Manual. This is often the result of being dehydrated, which can occur due to vomiting, diarrhea, sweating too much or taking diuretics.

As with sodium, potassium levels can become imbalanced.

A potassium deficiency, which is known as hypokalemia, can be caused by taking diuretics or laxatives, drinking alcohol to excess, diarrhea, excessive sweating and other factors, according to the Mayo Clinic. Hypokalemia can lead to weakness and fatigue, per the Mayo Clinic.

The cause of high levels of potassium (hyperkalemia) is often kidney disease, per the American Kidney Fund. When potassium levels are too high, it can lead to heart problems. Symptoms of hyperkalemia can include weakness, fatigue and nausea.

In general, people in the United States consume too much sodium (which is ever-present in packaged and processed foods), and too little potassium, according to the Centers for Disease Control and Prevention (CDC).

This can lead to heart problems: Too much sodium and too little potassium increases your blood pressure, per the CDC. Having potassium relaxes the blood vessel walls, according to the American Heart Association (AHA) — this, in turn, lowers blood pressure, helping to prevent heart disease and stroke.

Having more potassium has another side benefit: Potassium removes sodium from your body, according to the AHA. Along with upping your potassium intake, it's also wise to reduce your salt intake, per the AHA.

A basic metabolic panel blood test can measure the levels of potassium and sodium in the blood, according to the NIH.

Urine tests can also be used to detect electrolyte levels.

Normal potassium levels are between 3.6 and 5.2 millimoles per liter (mmol/L), according to the Mayo Clinic, while normal sodium levels are between 135 and 145 milliequivalents per liter (mEq/L), per the Mayo Clinic.

The treatment for an electrolyte imbalance depends somewhat on the cause — if an underlying condition is leading to the imbalance, that will need to be addressed.

Here are common treatment tactics:

• ​Hypokalemia:​ For low levels of potassium, the treatment is typically potassium supplements, which are given intravenously for severe cases, per the Cleveland Clinic.
• ​Hyperkalemia​: While treatment options for high potassium levels will vary based on the level of potassium, common options include taking diuretics or intravenous therapy, according to the Cleveland Clinic. Shifting away from a medication that caused high potassium levels can also help, per the Cleveland Clinic.
• ​Hypernatremia:​ When the sodium levels in the blood are too high, the treatment is typically to replace fluids intravenously, according to the Merck Manual.
• ​Hyponatremia:​ With too low levels of sodium, common first-line treatments are to cut down on how many fluids you take in or adjusting how you take diuretics, according to the Mayo Clinic.