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 Overview of Electrolytes Well over half of the body's weight is made up of water. Doctors think about the body's water as being restricted to various spaces, called fluid compartments. The three main compartments are... read more and Overview of Potassium's Role in the Body 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. (See also Overview of Electrolytes.) Most of the body’s... read more .)
Potassium 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. (See also Overview of Electrolytes.) Most of the body’s... read more is one of the body's electrolytes, which are minerals Overview of Minerals Minerals are necessary for the normal functioning of the body’s cells. The body needs relatively large quantities of Calcium Chloride Magnesium Phosphate read more 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 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.
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.
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.
Diagnosis of Hypokalemia
Measurement of potassium level in the blood
Sometimes measurement of 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 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.
Treatment of Hypokalemia
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:
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.
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.
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