Hypokalemia

Hypokalemia
Other names	Hypokalaemia, hypopotassaemia, hypopotassemia
An ECG in a person with a potassium level of 1.1 meq/L showing the classical changes of ST segment depression, inverted T waves, large U waves, and a slightly prolonged PR interval.
Specialty	Critical care medicine
Symptoms	Feeling tired, leg cramps, weakness, constipation, abnormal heart rhythm[1]
Complications	Cardiac arrest[1]
Causes	Diarrhea, medications like furosemide and steroids, dialysis, diabetes insipidus, hyperaldosteronism, hypomagnesemia, not enough intake in the diet[1]
Diagnostic method	Blood potassium < 3.5 mmol/L[1][2]
Treatment	Dietary changes, potassium supplements, based on the underlying cause[3]
Frequency	20% of people admitted to hospital[4]

Hypokalemia is a low level of potassium (K⁺) in the blood serum.^[1] Mild low potassium does not typically cause symptoms.^[3] Symptoms may include feeling tired, leg cramps, weakness, and constipation.^[1] Low potassium also increases the risk of an abnormal heart rhythm, which is often too slow and can cause cardiac arrest.^[1][3]

Causes of hypokalemia include vomiting, diarrhea, medications like furosemide and steroids, dialysis, diabetes insipidus, hyperaldosteronism, hypomagnesemia, and not enough intake in the diet.^[1] Normal potassium levels in humans are between 3.5 and 5.0 mmol/L (3.5 and 5.0 mEq/L) with levels below 3.5 mmol/L defined as hypokalemia.^[1][2] It is classified as severe when levels are less than 2.5 mmol/L.^[1] Low levels may also be suspected based on an electrocardiogram (ECG).^[1] The opposite state is called hyperkalemia that means high level of potassium in the blood serum.^[1]

The speed at which potassium should be replaced depends on whether or not there are symptoms or abnormalities on an electrocardiogram.^[1] Potassium levels that are only slightly below the normal range can be managed with changes in the diet.^[3] Lower levels of potassium require replacement with supplements either taken by mouth or given intravenously.^[3] If given intravenously, potassium is generally replaced at rates of less than 20 mmol/hour.^[1] Solutions containing high concentrations of potassium (>40 mmol/L) should generally be given using a central venous catheter.^[3] Magnesium replacement may also be required.^[1]

Hypokalemia is one of the most common water–electrolyte imbalances.^[4] It affects about 20% of people admitted to hospital.^[4] The word hypokalemia comes from hypo- 'under' + kalium 'potassium' + -emia 'blood condition'.^[5]