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S -K

S -K

Potassium is an essential mineral that is involved in the metabolism of the kidneys, central nervous system, heart, and muscles. We get potassium in food, but potassium from food does not influence the level of potassium in the blood.

Potassium is mainly present inside cells in the body. The body needs balanced potassium levels to support normal metabolism.

The kidney is the most important regulator of potassium, acting by decreasing or increasing the secretion of potassium into urine. A high or low potassium level is caused by a defect in this regulation or a loss of potassium in some other way. In addition, in a disorder, more potassium than normal can be released from cells to outside cells.

The secretion of potassium from the kidneys is influenced the acid-base balance in the blood, kidney function, and certain hormones (cortisol and aldosterone). The internal pH of cells and certain hormones (insulin and catecholamine) affects the release of potassium from cells to outside cells.

When should potassium levels be measured?

Blood potassium level is often measured as part of a routine check-up including the fluid-salt and acid-base balance of the body. Most commonly, potassium is tested when examining various heart, vein, and kidney diseases, together with sodium and creatinine.

Blood potassium levels can be disturbed for several reasons. Potassium levels can be measured in connection with the following situations, for example:

  • Vomiting
  • Diarrhoea
  • Muscle weakness
  • Arrhythmia
  • Fatigue
  • Eating disorders
  • Potassium replacement therapy
  • Monitoring diuretic therapy
What does a potassium test measure?

The majority of potassium in the body is inside cells, and only a fraction of it is in the bloodstream. The body regulates the level of potassium carefully. The potassium test tells us about the fluid balance of the body. Additional tests can be done to find out the cause of the high or low level of potassium.

Normally, the result is: 

Reference values: 3.6–5.0 mmol/l

Read more about defining reference values.

Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.

An excessive potassium level is known as hyperkalemia. The most common cause of hyperkalemia is kidney failure, in which the secretion of potassium into urine decreases and its level in the blood increases.

In addition, the following conditions often cause excessively high potassium values:

  • Certain drugs (e.g. some antihypertensive and heart drugs)
  • Insufficient hormone production in the adrenal glands (aldosterone)
  • Diabetic ketoacidosis, an acid state in the body caused by lack of insulin
  • Haemolysis, or breakdown of red blood cells, when drawing the blood sample
  • Diuretics (can increase or lower the potassium level)

Low potassium values can be seen in the following situations:

  • Vomiting
  • Strong sweats
  • Diarrhoea and use of laxatives
  • Severe malnutrition
  • When the adrenal cortex produces excessive hormones (aldosterone and cortisol)
  • Sodium (2382 S-Na)
  • Creatinine (2143 S-Krea)
  • Insulin (6040 fS-Insu)

SYNLAB test list: Potassium (2001 S-K, 1999 P-K) https://www2.synlab.fi/laboratoriokasikirja/tutkimuskuvaukset/kalium/

Terveyskirjasto health library: Kalium (P-K) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=snk03062&p_hakusana=kalium

Terveyskirjasto health library: Hypokalemia (alhainen veren kalium) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=dlk00857&p_hakusana=kalium

Terveyskirjasto health library: Hyperkalemia (kohonnut veren kalium) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=dlk00855&p_hakusana=kalium


Fasting is not required

This examination does not require fasting