potassium

and Eva Rudolf-Müller, doctor

Valeria Dahm is a freelance writer in the medical department. She studied medicine at the Technical University of Munich. It is particularly important to her to give the curious reader an insight into the exciting subject area of medicine and at the same time to maintain the content.

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Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

More about the experts All content is checked by medical journalists.

Potassium is one of the most important positively charged ions (cations) in the body. The mineral plays a key role in the transmission of signals between cells and also maintains the electrical voltage there. In addition, our body regulates its acidity (pH value) with the help of potassium, among other things. Find out here what your potassium level says about your health.

What is Potassium

Potassium is an essential mineral. 98 percent of it is inside the cell and only two percent in the space outside of cells. Due to its electrical charge, potassium ensures that the so-called resting potential is maintained between the cell interior and the cell exterior. However, if there is an influx of sodium into the cell and an outflow of potassium out of the cell, an action potential develops. It is used to transmit signals between cells, for example between individual nerve cells or between nerve cells and muscle cells.

Potassium also activates various enzymes, for example for protein synthesis. In addition, potassium and protons (also positively charged particles) can be exchanged between the cell interior and exterior due to their identical charge.This mechanism makes a decisive contribution to the regulation of the pH value.

Potassium is also involved in regulating blood pressure. Meanwhile, the World Health Organization recommends an increased intake of potassium in high blood pressure (hypertension), as this can lower both systolic and diastolic blood pressure. In addition, the risk of stroke has been shown to decrease for patients.

Uptake and excretion of potassium

Potassium is absorbed through food. It is present in virtually every food. Some foods, such as bananas, are particularly high in potassium. In the event of a potassium overdose, the hormone aldosterone stimulates the excretion of the mineral via the kidneys.

Daily potassium requirement

In general, adults should consume at least two grams of potassium per day. In individual cases, however, the daily requirement depends on age and state of health. For example, a higher intake can be useful in high blood pressure patients.

When is potassium in the blood determined?

Since even small deviations from the normal values can have far-reaching consequences such as cardiac arrhythmias, potassium is included in almost every blood test as standard.

The potassium measurement is particularly important if someone has symptoms that indicate a possible potassium deficiency or excess. Symptoms such as muscle weakness, constipation, and palpitations can indicate an excessive loss of potassium. If, on the other hand, the potassium is too high, it can lead to abnormal sensations, especially in the mouth area, muscle twitching and paralysis and, in the worst case, cardiac arrhythmias.

It is also important to monitor the potassium level in general with acute and chronic illnesses and when taking certain medications. These include:

Use of cardiac glycosides for heart failure (heart failure)
Use of water tablets (diuretics) for heart failure
Cardiac arrhythmias
Excess or lack of aldosterone (hyperaldosteronism or hypoaldosteronism)
Cushing's Syndrome
acute or chronic kidney failure

Potassium normal values

The potassium levels in the blood serum and blood plasma are usually as follows:

age	Normal potassium level in serum (mmol / l)
0 to 7 days of life	3,2 – 5,5
8 to 31 days of life	3,4 – 6,0
1 to 6 months	3,5 – 5,6
6 months to 1 year	3,5 – 6,1
> 1 year	3,5 – 6,1
adult	3,8 – 5,2

With normal nutrition, the potassium level in the urine is 30 - 100 mmol / 24h (measured in the 24-hour urine collection). With longer fasting it can drop to 10 mmol / 24h.

If there is a potassium deficiency (hypokalaemia), a urine test provides information on how the body is losing the mineral:

Potassium in urine> 20 mmol / l: loss of potassium through the kidneys
Potassium in urine <20 mmol / l: loss of potassium from the intestines

When is the potassium level lowered?

Reduced potassium levels (hypokalaemia) are usually caused by the fact that too much of the mineral is lost through the kidneys. This can have the following reasons, for example:

Therapy with dehydrating agents, glucocorticoids, mineral corticoids or amphotericin B (an anti-fungal agent)
Excess aldosterone (hyperaldosteronism)
Cushing's Syndrome
acute kidney weakness with increased urine output
increased potassium excretion from excessive consumption of licorice

The body can also lose potassium through the gastrointestinal tract through:

diarrhea
Vomit
Abuse of laxatives

If there is a shift in potassium from the intercellular space into the cell, less potassium can be detected in the blood. This happens in the following cases:

too high blood pH (alkalosis)
Vitamin B therapy for anemia
Insulin therapy for coma diabeticum (comatose emergency situation in diabetic patients)

If there are a lot of white blood cells (leukocytes) in the blood sample, incorrectly low potassium levels may be measured. The reason: the leukocytes absorb the mineral from the blood.

Potassium deficiency

You can find out more about an undersupply of potassium in the article Potassium Deficiency.

When is the potassium level increased?

If the potassium level is increased, the doctor speaks of hyperkalemia. There is too much potassium in the body especially when it is not excreted by the kidneys. Possible reasons:

acute renal failure (acute renal failure)
chronic kidney failure
Deficiency in aldosterone (hypoaldosteronism)
Deficiency of mineral corticoids (Addison's disease)

Various drugs can also cause potassium levels to be too high:

Potassium-sparing diuretics
Spironolactone (also a diuretic)
ACE inhibitors (antihypertensive agents)
Angiotensin II receptor antagonists (cardiovascular agents)
Non-steroidal anti-inflammatory drugs (NSAIDs such as diclofenac, ibuprofen, ASA)
Cyclosporin A (immune system inhibitor = immunosuppressant)
Co-trimoxazole (combination preparation of two antibiotics)
Pentamidine (anti-protozoal agent)

If there is an excessive release from the cell into the intercellular space, the potassium level is also increased. Possible causes:

massive breakdown of red blood cells (hemolysis) after injuries, burns, or surgery
low blood pH (acidosis)
diabetic coma with insulin deficiency
Overdose of heart medication (digitalis)
Cancer therapy with cytostatics

If the vein is blocked for too long when taking a blood sample, this can also lead to a breakdown of the red blood cells and thus to an incorrectly high potassium blood level during the measurement.

What to do if the potassium is increased or decreased

In the event of an acute rise in the potassium level, immediate measures are necessary, as life-threatening cardiac arrhythmias threaten. A rapid absorption of potassium into the cell can be brought about with the help of insulin and glucose or sympathomimetics (beta1 agonists): These substances can lower the blood values of potassium.

If the hyperkalemia is chronic, potassium-increasing drugs are discontinued. In addition, the patient has to eat a low-potassium diet.

Acute hypokalaemia is treated with intravenous administration of potassium chloride. If the potassium level is chronically reduced, drugs that may be responsible are discontinued and a high-potassium diet is initiated.

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