Potassium urine test

Definition

The potassium urine test measures the amount of potassium in a certain amount of urine.

Alternative Names

Urine potassium

How the Test is Performed

After you provide a urine sample, it is tested in the lab. If needed, the health care provider may ask you to collect your urine at home over 24 hours. Your provider will tell you how to do this. Follow instructions exactly so that the results are accurate.

How to Prepare for the Test

Your provider may ask you to temporarily stop taking any medicines that may affect the test results. Tell your provider about all the medicines you take, including:

• Corticosteroids
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Potassium supplements
• Water pills (diuretics)

DO NOT stop taking any medicine before talking to your provider.

How the Test will Feel

This test involves only normal urination. There is no discomfort.

Why the Test is Performed

Your provider may order this test if you have signs of a condition that affects body fluids, such as dehydration, vomiting, or diarrhea.

It may also be done to diagnose or confirm disorders of the kidneys or adrenal glands.

Normal Results

For adults, normal urine potassium values are generally 20 mEq/L in a random urine sample and 25 to 125 mEq per day in a 24 hour collection. Lower or higher urinary level may occur depending on the amount of potassium in your diet and the amount of potassium in your body.

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

A higher than normal urine potassium level may be due to:

• Diabetic acidosis and other forms of metabolic acidosis
• Eating disorders (anorexia, bulimia)
• Kidney problems, such as damage to kidney cells called tubule cells (acute tubular necrosis)
• Low blood magnesium level (hypomagnesemia)
• Muscle damage (rhabdomyolysis)

Low urine potassium level may be due to:

• Certain medicines, including beta blockers, lithium, trimethoprim, potassium-sparing diuretics, or nonsteroidal anti-inflammatory drugs (NSAIDs)
• Adrenal glands releasing too little hormone (hypoaldosteronism)

Risks

There are no risks with this test.

References

Kamel KS, Halperin ML. Interpretation of electrolyte and acid-base parameters in blood and urine. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 24.

Villeneuve P-M, Bagshaw SM. Assessment of urine biochemistry. In: Ronco C, Bellomo R, Kellum JA, Ricci Z, eds. Critical Care Nephrology. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 55.