A potassium urine test, also called a urine potassium test, checks the level of potassium in your urine. Potassium is a fundamental element in cell metabolism.
Excessive potassium (hyperkalemia) can cause nausea, fatigue, and muscle weakness. If it goes undetected and is left untreated, hyperkalemia can be dangerous and possibly even fatal. However, hyperkalemia is not always detected before it causes symptoms. Common causes for high potassium include kidney dysfunction or injury and diseases of the adrenal gland. Some medications can also cause hyperkalemia.
Too little potassium is called hypokalemia. A severe loss or drop in potassium can cause heart arrhythmia, muscle weakness or spasms, and paralysis. Common causes for a drop in potassium include vomiting, sweating, and diarrhea. Medications, particularly antibiotics, are also known to cause hypokalemia.
Your doctor may order a potassium urine test:
- to check potassium levels if you have been vomiting, have had diarrhea for several hours or days, or show signs of dehydration
- to confirm hyperkalemia or hypokalemia
- to diagnose a kidney disease or injury, such as medullary cystic kidney disease
- to diagnose adrenal gland problems, such as hypoaldosteronism and Conn’s syndrome
- to verify a low or high blood potassium test result
- to monitor possible side effects of medications or drug treatments
A high potassium urine result may be caused by:
- acute tubular necrosis
- eating disorders (anorexia and bulimia)
- kidney disease
- low blood magnesium levels (hypomagnesaemia)
- medicines, such as antibiotics, blood thinners, nonsteroidal anti-inflammatory drugs (NSAIDs), and blood pressure medication
- renal tubular acidosis
- use of diuretics
- uncontrolled diabetes
A low potassium urine result may be caused by:
- adrenal gland insufficiency
- eating disorders (bulimia)
- excessive sweating
- kidney disease
- laxative use
- magnesium deficiency
- certain medicines, including beta blockers and nonsteroidal anti-inflammatory drugs (NSAIDs)
- vomiting or diarrhea
Two collection types are used for a potassium urine test. The first is a single random urine sample. The second is a 24-hour urine sample.
For a random urine sample, you will be asked to urinate into a collection cup at your doctor’s office or lab facility. You will give the cup to a nurse or lab technician, and it will be sent to a lab for testing.
For a 24-hour urine sample, you will collect all your urine from a 24-hour window into a large container. To do this, you will begin your day by urinating into the toilet. After that initial urination, you will begin collecting your urine each time you urinate. After 24 hours, you will turn over your collection container to a nurse or lab technician with your doctor’s office. The sample will be sent for testing.
A potassium urine test has no risks. It involves normal urination. This test should not cause any discomfort.
Before a potassium urine test, ask your doctor if you should temporarily stop taking any prescription medications, or if you should avoid taking certain over-the-counter medications or supplements. Drugs and supplements that can affect the results of a potassium urine test include:
- beta blockers
- blood pressure medication
- diabetes medications or insulin
- herbal supplements
- potassium supplements
- nonsteroidal anti-inflammatory drugs (NSAIDs)
Your doctor or a nurse may instruct you to clean your genital area before you begin each urine sample collection. You will also need to keep the urine sample clean from pubic hair, stool, menstrual blood, toilet paper, and other potential contaminants.
If you have any questions or concerns about the potassium urine test and how to collect your urine samples, talk with your doctor or nurse.
A normal potassium range, or a reference range, for an adult is 25 to 125 milliEquivalents per liter (mEq/L) per day. A normal potassium level for a child is 10 to 60 mEq/L. These ranges are only a guide, and actual ranges vary from doctor to doctor and lab to lab. Your lab report should include a reference range for normal, low, and high potassium levels. If it does not, ask your doctor for one, or contact the lab that processed your urine sample to get one.
Following a potassium urine test, your doctor may also request a potassium blood test if he or she believes it can help diagnose or detect a problem that the urine test did not detect. Your doctor may also use a blood test to confirm a diagnosis.