In hypokalemia, the level of potassium in blood is too low.
A low potassium level has many causes but usually results from vomiting, diarrhea, adrenal gland disorders, or use of diuretics.
A low potassium level can make muscles feel weak, cramp, twitch, or even become paralyzed, and abnormal heart rhythms may develop.
The diagnosis is based on blood tests to measure the potassium level.
Usually, eating foods rich in potassium or taking potassium supplements by mouth is all that is needed.
(See also Overview of Electrolytes and Overview of Potassium's Role in the Body.)
Potassium is one of the body's electrolytes, which are minerals that carry an electric charge when dissolved in body fluids such as blood. Potassium is needed for cells, muscles, and nerves to function correctly.
Causes of Hypokalemia
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 the person is using medications that cause the kidneys to excrete excess sodium, water, and potassium (diuretics).
In many adrenal disorders, such as Cushing syndrome, the adrenal glands produce too much aldosterone, a hormone that causes the kidneys to excrete large amounts of potassium.
Certain medications (such as insulin
Hypokalemia sometimes occurs with or is caused by a low level of magnesium in the blood (hypomagnesemia).
Hypokalemia is rarely caused by consuming too little potassium because many foods (such as beans, dark leafy greens, potatoes, fish, and bananas) contain potassium.
What Makes the Potassium Level Decrease?
Cause | Disorders | Medications or Other Factors |
|---|---|---|
Increased loss from the digestive tract (most common) | Diarrhea Vomiting | Laxatives if used a long time |
Increased excretion in urine | Increased production of aldosterone due to a tumor in the adrenal glands A low level of magnesium (hypomagnesemia) | Diuretics (commonly) Licorice (natural) if consumed in large amounts Tobacco chewing (certain types) |
Increased movement from blood into cells | An overactive thyroid gland (hyperthyroidism) | Insulin Some medications used to treat asthma |
Symptoms of Hypokalemia
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.
If hypokalemia lasts for an extended time, kidney problems may develop, causing the person to urinate frequently and drink large amounts of water.
Diagnosis of Hypokalemia
Measurement of the potassium level in the blood
Electrocardiography
Sometimes measurement of the amount of potassium in urine
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 medications 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 (ECG) to check for abnormal rhythms.
Treatment of Hypokalemia
Potassium supplements
If a disorder is causing hypokalemia, it is treated.
To treat hypokalemia more rapidly, potassium is given by vein (intravenously) in the following situations:
The potassium level is dangerously low.
The low level causes abnormal heart rhythms.
Supplements taken by mouth are ineffective.
People continue to lose more potassium than can be replaced using supplements taken by mouth.
When hypomagnesemia occurs with hypokalemia, it too is treated.
