Hypokalemia (Low Level of Potassium in the Blood)

Typically, the potassium level becomes low because too much is lost from the digestive tract due to vomiting, diarrhea, or excessive laxative use.

Sometimes too much potassium is excreted in urine, usually because of drugs that cause the kidneys to excrete excess sodium, water, and potassium (diuretics).

In many adrenal disorders, such as Cushing syndrome Cushing Syndrome In Cushing syndrome, the level of corticosteroids is excessive, usually due to taking corticosteroid drugs or overproduction by the adrenal glands. Cushing syndrome usually results from taking... read more , the adrenal glands produce too much aldosterone, a hormone that causes the kidneys to excrete large amounts of potassium.

Certain drugs (such as insulin, albuterol, and terbutaline) cause more potassium to move from blood into cells and can result in hypokalemia. However, these drugs usually cause temporary hypokalemia, unless another condition is also causing potassium to be lost.

Hypokalemia sometimes occurs with or is caused by a low level of magnesium in the blood (hypomagnesemia Hypomagnesemia (Low Level of Magnesium in the Blood) In hypomagnesemia, the level of magnesium in blood is too low. (See also Overview of Electrolytes and Overview of Magnesium's Role in the Body.) Magnesium is one of the body's electrolytes,... read more ).

Hypokalemia is rarely caused by consuming too little potassium because many foods (such as beans, dark leafy greens, potatoes, fish, and bananas) contain potassium.

A slight decrease in the potassium level in blood usually causes no symptoms.

A larger decrease can cause muscle weakness, cramping, twitches, and even paralysis.

Abnormal heart rhythms Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more may develop. They may develop even when the decrease is slight if people already have a heart disorder or take the heart drug digoxin.

If hypokalemia lasts for an extended time, kidney problems may develop, causing the person to urinate frequently and drink large amounts of water.

The diagnosis is made by measuring a low potassium level in the blood. Doctors then try to identify what is causing the potassium level to decrease.

The cause may be clear based on the person’s symptoms (such as vomiting) or use of drugs or other substances. If the cause is not clear, doctors measure how much potassium is excreted in urine to determine whether excess excretion is the cause.

Because low potassium levels can cause abnormal heart rhythms, doctors usually do electrocardiography Electrocardiography Electrocardiography (ECG) is a quick, simple, painless procedure in which the heart’s electrical impulses are amplified and recorded. This record, the electrocardiogram (also known as an ECG)... read more (ECG) to check for abnormal heart rhythms.

If a disorder is causing hypokalemia, it is treated.

Usually, potassium can be replaced by taking potassium supplements by mouth. Because potassium can irritate the digestive tract, supplements should be taken in small doses with food several times a day rather than in a single large dose. Special types of potassium supplements, such as wax-impregnated or microencapsulated potassium chloride, are much less likely to irritate the digestive tract.

To treat hypokalemia more rapidly, potassium is given by vein (intravenously) in the following situations:

Most people who take diuretics do not need to take potassium supplements. Nevertheless, doctors periodically check the potassium level in blood so that supplements can be given if necessary. Alternatively, diuretics that help the kidneys conserve potassium (potassium-sparing diuretics), such as amiloride, eplerenone, spironolactone, or triamterene can be used, but these drugs are used only if the kidneys are functioning normally.

When hypomagnesemia Hypomagnesemia (Low Level of Magnesium in the Blood) In hypomagnesemia, the level of magnesium in blood is too low. (See also Overview of Electrolytes and Overview of Magnesium's Role in the Body.) Magnesium is one of the body's electrolytes,... read more occurs with hypokalemia, it too is treated.