Evidence Based

Potassium Blood Tests: The Risks of Low or High Levels

Written by Biljana Novkovic, PhD | Last updated:

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Serum potassium is an electrolyte that is key to proper hydration, and high or low-level serum potassium can be a sign of an underlying health issue. People go to their doctor to get their potassium tested as part of a standard panel. Almost always, the results are not scrutinized, even though we know that you can be healthier and live longer when your results lie within optimal ranges. When I used to go to doctors and tried to discuss my results, they had no clue what these meant from a health perspective. All they cared about was whether they could diagnose me with some disease.

What is Potassium?

Potassium in The Human Body

Potassium is an essential mineral that the body uses to regulate blood pressure, heartbeat, muscle contractions, nerve impulses, and digestion [1]. Potassium is estimated to be the 8th or 9th most common element in the human body [2].

The majority of the body’s potassium is located inside the cells, where it is involved in the production of proteins, helps maintain water balance, plays a role in cell division and accelerates chemical reactions [34]. The largest storage of potassium in the human body is in the muscles [5].

The blood levels of potassium, called serum potassium in medical literature, amount to only about 2% of the total body potassium [5].

Since most of the potassium in the body is inside of cells, serum potassium levels are determined by the transportation of this mineral into or out of the cells [6, 7].

The kidneys maintain total potassium and other electrolytes in the body [68].

Potassium can be lost due to conditions which cause dehydration, such as physical activity, high temperatures, and diarrhea [9].

Reference Ranges For Serum Potassium

Even minor departures from the recommended range are associated with significant morbidity and mortality [10].

Potassium levels are considered high (hyperkalemia) when the value is 5.5 mmol/L or greater, and low (hypokalemia) when the value is 3.5. mmol/L or less [11].

Several factors contribute to variations in serum potassium levels. A study showed that serum potassium was lowest in the evening (around 9 p.m.) and highest in the early afternoon (1 – 3 p.m.) [12].

Average ranges of serum potassium can vary for people in different geographic locations, likely as a result of dietary differences [13]. Men in China have lower serum potassium levels than averages in other parts of the world [13].

In the United States, serum potassium concentrations are lower in African Americans than in people of European ancestry [14].

During pregnancy, it is normal that potassium levels are higher because the kidneys eliminate less potassium; increases in the hormone progesterone could be responsible for adapting the body to this change.

Finally, your potassium may be in the reference range, but not actually be in the optimal range. Sometimes even the ‘normal’ range can be unhealthy and indicate that certain processes in the body aren’t optimal.

Why is Low Serum Potassium Bad?

Clinically low serum potassium (hypokalemia) can lead to severe disturbances in heart, brain, and muscle functions [15].

An imbalance in serum potassium levels is often the result of kidney diseases or intestinal diseases leading to dehydration and electrolyte imbalances [7].

Serum potassium in healthy people does not vary significantly with dietary potassium or the amount of potassium stored in the body [16]. As a result, poor potassium intake is often not the true cause of hypokalemia. However, people with extremely poor diets and people on severe weight-reduction programs are in danger of developing severe potassium deficiency [17181019].

Why is High Serum Potassium Bad?

Left unaddressed, moderate to severely elevated serum potassium (hyperkalemia) can lead to disturbances of the heart rhythm, which can be fatal [20]. Extremely high serum potassium should thus be handled as an emergency, and monitoring levels of those at risk is essential [20].

High serum potassium may result from dehydration and electrolyte imbalance due to kidney disease, heart disease, adrenal insufficiency, and gut ulcers [2112]. Older patients, patients with chronic heart failure, kidney failure, and diabetic patients are prone to developing hyperkalemia [8].

Diseases Associated with Abnormal Serum Potassium Levels

1) Serum Potassium and Elevated Blood Pressure

Lower serum potassium levels are generally associated with higher blood pressure [22].

Drugs used to lower blood pressure are a significant cause of low serum potassium (hypokalemia) and often require systematic monitoring of blood potassium levels during treatment [2223].

The overall link between high blood pressure and serum potassium levels remains somewhat unclear. One study found that high potassium intake lowers blood pressure in people with hypertension and, to a lesser extent, in people with normal blood pressure [24]. However, another study showed that higher than average serum potassium increased the risk of hypertension in a Chinese population [25]. Potassium levels outside the upper limits of the normal high range were associated with increased mortality risk in patients with hypertension [23]. Because potassium is involved in regulating a number of processes, it is likely that both the blood pressure changes and potassium levels are downstream results of other conditions.

2) Serum Potassium and Insulin Resistance

Studies have found that serum potassium levels can predict the development of glucose intolerance, a risk factor that can lead to diabetes [14].

Poor dietary choices are thought to be a major cause of both insulin resistance and potassium level disturbances [26]. Possibly, poor serum potassium levels may be a warning sign of poor health rather than a direct cause of insulin resistance.

A link between poor blood sugar control and low serum potassium has been confirmed in several studies. Low serum potassium is associated with poor metabolic function typical in diabetes, including high levels of triglycerides, lower levels of high-density lipoprotein cholesterol (HDL-C), larger waist circumference, and more severe insulin resistance [27].

Lower serum potassium is associated with poor blood sugar control in metabolic syndrome patients [28]. Lower serum potassium levels are also associated with prediabetes in adults with elevated blood pressure [29].

Serum potassium levels are generally lower in African Americans compared to people with European ancestry. These differences in serum potassium may help explain why African Americans are at higher risks of developing diabetes [14].

Interestingly, serum potassium levels are higher in patients with more poorly controlled type 2 diabetes [30]. Because poorly managed diabetes decreases kidney function, it is likely that the high potassium in these conditions is due to the inability of the kidneys to maintain proper levels of potassium.

After a 5 year follow-up period, in people under 40, every 1 mmol/L increase in serum potassium within the normal range decreased the odds of having elevated glucose and overt diabetes. However, in people over 40, the opposite relationship was found. It was suggested that the aging kidney and decreased aldosterone levels may influence the relationship in the older population [31].

3) Serum Potassium and Metabolic Syndrome

Metabolic syndrome is the name for a group of health issues that are risk factors for stroke and diabetes, including high cholesterol, insulin resistance, and blood sugar disturbances [32]. Low serum potassium was significantly associated with the prevalence of metabolic syndrome indicators in middle-aged and elderly subjects [27]. Serum potassium levels significantly decreased with an increasing number of metabolic syndrome symptoms [27].

Poor dietary choices are thought to be the major cause of both metabolic syndrome and potassium level disturbances [26]. As a result, poor serum potassium levels are likely a warning sign of an underlying issue rather than a cause of metabolic syndrome.

4) Serum Potassium and Fatty Liver Disease

In children with fatty liver, low serum potassium is associated with liver inflammation and damage. The likelihood of having liver damage decreases by 76% for every 0.5 mmoL/L increase in potassium, supporting a strong connection between potassium and fatty liver [26].

Researchers have suggested that poor potassium levels and fatty liver are both due to poor diet and nutrition [26]. Therefore, poor serum potassium levels may not contribute directly to fatty liver, but that they are a warning sign of other risk factors.

Low serum potassium is associated with a higher prevalence of nonalcoholic fatty liver disease (NAFLD) in middle-aged and elderly Chinese patients. The patients with lower serum potassium level had larger waist circumference and more severe insulin resistance [33].

5) Serum Potassium and Cardiovascular Disease

Both low and high serum potassium levels are associated with an increased risk of cardiovascular events and mortality [34].

Alterations in serum potassium levels can cause irregular heartbeats [35].

Studies of elderly patients have confirmed that both high and low serum potassium levels are associated with cardiovascular events and mortality [36].

In the elderly, lower serum potassium is also associated with increased stroke [37].

6) Serum Potassium and Kidney Disease

Because the kidneys balance the potassium levels in the body, serum potassium abnormalities are very common among kidney disease patients. Patients with impaired kidney function have higher fluctuations of serum potassium during the day [12]. Both low and high potassium have been consistently associated with a high risk of all-cause and cardiovascular mortality among kidney disease patients [38]. 2 to 5% of deaths in the end-stage kidney disease are associated with high potassium [39].

Serum potassium normalization in chronic kidney disease patients is also associated with disease improvements [11404142].

7) Serum Potassium and Anxiety and Depression

Anxiety causes the body to increase the level of the stress hormone adrenaline, which causes cells to take up potassium and thus lowering serum potassium levels [43]. Low potassium levels can thus be an indicator of anxiety in some cases.

Low potassium is significantly associated with major depression, anxiety, and suicidal attempts in patients with acetaminophen (paracetamol) overdose [44]. Overproduction of the stress neurotransmitters adrenaline and epinephrine, which lower serum potassium, may explain this relationship [44].

Decreases in serum potassium are associated with increased anxiety before surgery [45].

In schizophrenic men, low serum potassium was associated with acute agitation. Serum potassium concentration in the severely agitated group was lower than in the mildly agitated group. Sedation increased serum potassium levels (improved hypokalemia) in agitated patients [46].

Factors that Increase Serum Potassium

1) Potassium-Rich Food

Increasing potassium intake can decrease blood pressure, lower the risk of cardiovascular disease, diabetes, metabolic syndrome and chronic kidney disease [47, 48, 49, 50, 51]. Since cardiovascular and kidney disease are associated with poor serum potassium control, improvements in these disease states lead to improvements in the body’s ability to manage serum potassium levels.

Potassium concentration is higher in fruits and vegetables than in cereals and meat, and many commonly consumed fruits and vegetables are good sources of potassium [5].

Salting foods and discarding the liquid induces a sodium for potassium exchange and reduces the potassium content of the foods [5]. Western dietary practices with higher consumption of cereal, low nutrient density processed foods and lower consumption of fruits and vegetables have led to a diet lower in potassium and higher in sodium in recent decades [5]. It has been suggested that potassium intake relative to sodium intake is lower than the World Health Organization recommendations in the United States and Europe, suggesting that there may be health benefits to improving potassium consumption [4037].

2) Potassium Supplements

Potassium supplements are commonly used to treat low levels of potassium in patients who do not have enough potassium in their regular diet or have lost potassium due to illness or treatment with certain medication.

In elderly men, the long-term use of potassium-enriched salts can prolong life expectancy and reduce the mortality linked to cardiovascular disease [52, 53].

In short-term studies of relatively healthy people, a moderate oral potassium supplement resulted in a small increase in serum potassium levels and no change in kidney function. The increase was neither associated with the dose nor duration of the treatment [24].

Supplemental potassium should be provided under medical supervision due to potential toxicity [54], especially if you have kidney problems [55].

See my post on Potassium Supplements.

3) Exercise Temporarily Increases Serum Potassium

During an intense workout, serum potassium is doubled per minute resulting in high potassium levels. However, potassium levels rapidly return back to normal for healthy people [6].

The magnitude of exercise-induced hyperkalemia depends on fitness levels. Exercise-induced hyperkalemia is significantly reduced in well-trained individuals comparing to less well-trained individuals [6].

4) Drugs that Interfere with Catecholamines or Aldosterone

Both drugs that interfere with catecholamines such as beta blockers, and those that interfere with aldosterone, are used as blood pressure-reducing agents. Beta-blockers are also used to treat irregular heartbeat (arrhythmias).

Drugs that block catecholamine receptors, such as beta blockers, decrease the uptake of potassium by the cells and therefore increase serum potassium levels [5657].

Similarly, drugs that block aldosterone decrease the excretion of potassium from the kidneys, resulting in higher potassium retention. Lisinopril and spironolactone, for example, can have adverse effects on serum potassium [5859].

5) Proton Pump Inhibitors

A study showed that proton pump inhibitor (PPI, a type of drug that reduces stomach acid) users had significantly higher serum potassium levels than non-users. However, in this study, high-dose PPI therapy was not associated with an increased risk for hyperkalemia [60].

Hyperkalemia, along with other symptoms of dehydration, has been reported with intravenous use of the proton pump inhibitor omeprazole [61].


NSAIDs (non-steroidal anti-inflammatory drugs) can diminish the elimination of potassium, which can cause high serum potassium [8].

7) Adrenal Insufficiency

Hormones produced in the adrenals are strongly involved in managing blood pressure and potassium levels [62]. Adrenal insufficiency often results in lowered production of the hormone aldosterone, leading to increased serum potassium levels [8].

Patients who have reduced aldosterone due to adrenal removal are at risk for developing moderate-to-severe hyperkalemia [63].

Factors that Reduce Serum Potassium

1) Caffeine

Caffeine can reduce serum potassium levels by increasing the release of adrenaline [64].

Excessive ingestion of caffeine-containing beverages can induce hypokalemia [65].

2) Insulin

Insulin stimulates the transport of potassium from the blood into the cells, thereby lowering serum potassium levels [5]. High insulin due to insulin insensitivity can thus lead to dangerously low serum potassium levels.

3) Adrenaline Release

Adrenaline and epinephrine, the neurotransmitters associated with the “fight-or-flight” response, stimulate the transport of potassium from the blood into the cells, thereby lowering serum potassium levels [5].

Anxiety, which increases adrenalin and epinephrine, has been shown to lead to decreased serum potassium [45].

Theophylline is a drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) that increases adrenalin. Theophylline intoxication can result in hypokalemia [6667].

4) Diuretics

The most common cause of potassium depletion is the use of diuretics, drugs which remove excess water in the body [68].

In hypertensive patients, serum potassium was significantly lower among patients receiving diuretics and hypokalemia was found to be significantly more prevalent in this group [22].

5) Paracetamol

Paracetamol causes a concentration-dependent reduction of potassium concentrations, and this is one of the risks associated with paracetamol overdose [69, 44].

6) Drugs – Other

A reduction in serum potassium is a side-effect of a variety of drugs, including beta-adrenergic agonists, antibiotics, and glucocorticoids [70].

Chloroquine (used to treat malaria) also decreases serum potassium and overdose can result in hypokalemia [71].

In 2016 the FDA approved the drug Veltassa to treat high serum potassium (hyperkalemia). Veltassa increases binding to potassium in the intestines, increasing its elimination [72].

Irregular Potassium Levels?

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About the Author

Biljana Novkovic

Biljana received her PhD from Hokkaido University.
Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science & health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.

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