What is potassium?
Potassium also activates various enzymes, for example for protein synthesis. In addition, potassium and protons (also positively charged particles) can be exchanged between the interior and exterior of cells due to their equal charge. This mechanism contributes decisively to the regulation of the pH value.
Absorption and excretion of potassium
Potassium is absorbed through food. It is present in virtually every food. Some foods, such as bananas, contain particularly high levels of potassium. In the case of a potassium overdose, the hormone aldosterone stimulates the excretion of the mineral through the kidneys.
Potassium daily requirement
When is potassium determined in the blood?
Since even small deviations from the normal values can have far-reaching consequences, such as cardiac arrhythmias, potassium is determined as standard in almost every blood test.
It is also generally important to monitor potassium levels in acute and chronic illnesses and when taking certain medications. These include:
- Taking cardiac glycosides in the case of cardiac insufficiency (heart failure)
- @ Taking diuretics in heart failure @ Taking potassium supplements in heart failure
- Cardiac arrhythmias
- Excess or deficiency of aldosterone (hyperaldosteronism or hypoaldosteronism)
- Cushing’s syndrome
- acute or chronic kidney failure
Potassium standard values
|
Age |
Standard serum potassium value (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 |
|
Adults |
3,8 – 5,2 |
Urinary potassium level is 30 – 100 mmol/24h under normal diet (measured in 24-hour collected urine). During prolonged fasting, it may drop to 10 mmol/24h.
If there is a potassium deficiency (hypokalemia), a urine examination provides information about the way in which the body loses the mineral:
- Potassium in urine < 20 mmol/l: potassium loss via the intestine
When is the potassium level decreased?
Decreased potassium levels (hypokalemia) usually result from too much of the mineral being lost via the kidneys. This can have the following reasons, for example:
- Therapy with drainage agents, glucocorticoids, mineral corticoids, or amphotericin B (an antifungal agent).
- Excess of aldosterone (hyperaldosteronism)
- Cushing’s syndrome
- acute kidney weakness with increased urine output
The body can also lose potassium through the gastrointestinal tract:
- Diarrhea
- Vomiting
- abuse of laxatives
If there is a shift of potassium from the intercellular space into the cell, less potassium is also detectable in the blood. This happens in the following cases:
- excessively high blood pH (alkalosis)
- Vitamin B therapy for anemia (anemia)
- insulin therapy in coma diabeticum (comatose emergency situation in diabetes patients)
Potassium deficiency
You can learn more about an undersupply of potassium in the article Potassium Deficiency.
When is the potassium level elevated?
If the potassium is elevated, the doctor speaks of hyperkalemia. Too much potassium in the body is mainly present when excretion via the kidneys is reduced. Possible reasons:
- acute kidney failure (acute renal insufficiency)
- chronic kidney failure
- deficiency of aldosterone (hypoaldosteronism)
- deficiency of mineral corticoids (Addison’s disease)
- Potassium-sparing diuretics
- Spironolactone (also a diuretic)
- ACE inhibitors (antihypertensives)
- Angiotensin II receptor antagonists (cardiovascular drugs)
- Non-steroidal anti-inflammatory drugs (NSAIDs such as diclofenac, ibuprofen, ASA)
- Cyclosporin A (immune system inhibitor = immunosuppressant)
- Cotrimoxazole (combination preparation of two antibiotics)
- Pentamidine (agent against unicellular parasites = antiprotozoal drug)
- massive decay of red blood cells (hemolysis) after injuries, burns or operations
- excessively low blood pH (acidosis)
- diabetic coma with insulin deficiency
- overdose of heart medication (digitalis)
- cancer therapy with cytostatics
If the vein is congested for too long during blood sampling, this can also lead to a breakdown of the red blood cells and thus to a falsely high potassium blood value when measured.
What to do if the potassium is increased or decreased?
If the hyperkalemia is chronic, potassium-increasing drugs are discontinued. In addition, the patient must follow a low-potassium diet.
Acute hypokalemia is treated with intravenous administration of potassium chloride. If potassium is chronically decreased, any responsible medications are discontinued and a high-potassium diet is initiated.
