Potassium

A potassium blood test is used to detect abnormal potassium levels, including high potassium (hyperkalemia) and low potassium (hypokalemia). It is often used as part of an electrolyte panel or basic metabolic panel for a routine health exam.

The potassium test may also be used:

• To help detect, evaluate, and monitor electrolyte imbalances and/or acid-base (pH) imbalances (acidosis or alkalosis)
• To help evaluate and monitor a variety of chronic or acute illnesses, such as high blood pressure or kidney disease, the most common cause of high blood potassium 
• To detect abnormal values when you have diarrhea and vomiting or excessive sweating
• To help determine the cause of symptoms involving the heart (e.g., irregular heart beat)
• To monitor effects of drugs that can cause the kidneys to lose potassium, particularly diuretics, or drugs that decrease potassium elimination from the body, which may result in a high potassium level

Urine potassium levels may be tested in people who have abnormal blood potassium levels to help determine the cause, such as dehydration. Urine potassium testing is also used for people with abnormal kidney tests to help the healthcare practitioner determine the cause of kidney disease and to help guide treatment.

A potassium level is a basic test and may be ordered when you have a routine medical exam or when you are being evaluated for a serious illness.

Testing may be done when you have:

• Kidney disease
• Symptoms such as muscle weakness or irregular heart beat (cardiac arrhythmia)
• A condition treated with diuretics or heart medications
• Has high blood pressure (hypertension) or are being treated for high blood pressure

Electrolyte panels and basic metabolic panels are commonly ordered at regular intervals when a healthcare practitioner is diagnosing diabetic ketoacidosis and kidney disease or when monitoring a patient receiving dialysis, diuretic therapy, or intravenous fluids.

Urine potassium testing may be done when blood potassium levels are abnormal.

Potassium levels are typically interpreted along with results from other tests done at the same time, such as the results of other electrolyte tests. Low and high potassium levels can be caused by various conditions and diseases.

Examples of conditions that can cause high potassium levels (hyperkalemia) include:

• Kidney disease
• Addison disease
• Injury to tissue
• Infection
• Diabetes
• Dehydration
• Consuming too much potassium (e.g., diets high in potassium, potassium supplements)
• Treatment with intravenous (IV) fluids, excessive IV potassium
• Using certain drugs that cause high potassium in a small percent of people, including non-steroidal anti-inflammatory drugs (NSAIDs), ACE inhibitors, beta blockers (such as propranolol and atenolol), angiotensin-converting enzyme inhibitors (such as captopril, enalapril, and lisinopril), and potassium-sparing diuretics (such as triamterene, amiloride, and spironolactone)

Examples of conditions that can cause low potassium levels (hypokalemia) include:

• Diarrhea and vomiting
• Primary hyperaldosteronism (Conn syndrome)
• A complication of acetaminophen overdose
• Diabetes - the potassium level may fall after you take insulin, particularly if you have not managed your diabetes well.
• As a side-effect of "water pills" (potassium-wasting diuretics); if you take these, your healthcare provider may check your potassium level regularly.
• Use of certain drugs such as corticosteroids, beta-adrenergic agonists such as isoproterenol, alpha-adrenergic antagonists such as clonidine, antibiotics such as gentamicin and carbenicillin, and the antifungal agent amphotericin B

Potassium urine levels are usually compared with blood levels. The body normally eliminates excess potassium, so the urine level may be elevated because it is elevated in the blood. Urine potassium may also be elevated when the body is losing too much potassium. In this case, the blood level would be normal to low. If blood potassium levels are low due to not consuming enough, then urine concentrations will also be low.

• Decreased urine potassium levels may be due to certain drugs such as NSAIDs, beta blockers, and lithium or due to the adrenal glands producing too little of the hormone aldosterone.
• Increased urine potassium levels may be due to kidney disease, eating disorders such as anorexia, or muscle damage.

Your potassium result is interpreted by your healthcare practitioner within the context of other tests that you have had done as well as other factors, such as your medical history. A single high or low result may or may not have medical significance. Generally, this is the case when the test value is only slightly higher or lower than the reference range. This is why healthcare practitioners may repeat a test on you and why they may look at results from prior times when you had the same test performed.

On the other hand, a result outside the range may indicate a problem and warrant further investigation. Your healthcare practitioner will evaluate your test results and determine whether a result that falls outside of the reference range means something significant for you.

Treatment for low potassium may include taking potassium chloride supplements and eating more potassium-rich foods, such as bananas, beef or spinach. Treatment for high potassium may include the use of diuretics, kidney dialysis, or insulin injections.