A potassium urine test looks at the amount of potassium in your urine. It may be done as a 24-hour urine sample or a random one-time sample.
Potassium is an electrolyte. It balances the sodium in your body. It also helps to control your body’s fluid levels.
Potassium has many important functions in your body. It is very important for muscle and nerve health. Having too much or too little potassium in your body can cause symptoms such as:
- muscle cramps
- low blood pressure
A potassium urine test is often used to check kidney health. It can also be used to monitor whether certain medications, such as diuretics, are affecting your potassium levels. Finally, it can be used to help diagnose adrenal disorders or electrolyte imbalances.
Too much potassium in your urine can be caused by:
- eating disorders, including anorexia and bulimia
- hypomagnesaemia (low blood magnesium)
- diabetic acidosis
- kidney disease or failure
- taking non–potassium-sparing diuretics
- Cushing syndrome, from exposure to too much cortisol (rare)
- hyperaldosteronism (high aldosterone levels—rare)
Low levels of potassium can be caused by:
- hypoaldosteronism (low aldosterone)
- adrenal gland insufficiency, or Addison’s disease
- certain medications, such as beta-blockers, lithium, potassium-sparing diuretics, and non-steroidal anti-inflammatory drugs (NSAIDs)
- cell lysis syndrome, caused by cancer treatment
Your doctor may also order a potassium urine test to monitor treatment for high or low potassium levels.
It is important that you tell your doctor about all medications you are taking. Be certain to include both over-the-counter and prescription medications.
Your doctor may ask you to stop taking certain drugs or reduce your doses before this test. Medications that can affect urine potassium include:
- antibiotics that contain potassium, such as penicillin
- diuretics (water pills)
- insulin or glucose
- non-steroidal anti-inflammatory drugs (NSAIDs)
Clean-Catch Urine Collection
A urine potassium test requires a clean-catch urine sample.
Start by washing your hands thoroughly. Remove the lid from the cup, being careful not to touch the inside of the lid or cup. Use the moist towelette or swab you were given to clean the area around your urethra. Throw it away.
Begin urinating into the toilet. After several seconds, place the collection cup in your urine stream. Collect about two ounces of urine, being careful not to touch the cup to your skin or the toilet. Finish urinating into the toilet.
Replace the cap on the collection cup. Make certain it is secure. Then, follow the instructions you were given for returning the sample to your doctor. If it will be more than an hour before you can return the sample, place it in the refrigerator.
Random One-Time Sample
A random one-time sample can be done in your doctor’s office. You may also be given a collection cup to take your sample at home.
To collect this sample, follow the clean-catch procedure described above. You only need to do so once.
24-Hour Urine Sample—Child or Adult
A 24-hour urine sample is the most common way to test urine potassium. For this test, you will be given a large collection container. It may contain some preservative. You will also be given several medicated wipes or swabs. These will be used to clean around your urethra before you urinate each time.
This test begins in the morning. When you first wake up, urinate into the toilet. Do not collect the urine, but note the time.
For the next 24 hours, you will collect urine every time you urinate. Each time, perform a clean-catch technique as described above. Between each urination, cover the container with the lid and place it in the refrigerator.
When you wake up on the morning of the second day, urinate into the container (clean catch) one final time. Then follow the instructions for labeling the container and returning it to the lab.
24-Hour Urine Sample—Infant
The technique for collecting clean catch urine from an infant is different. You will be given several urine collection bags as well as wipes and a collection container.
Each time you change the infant’s diaper, use the wipes to clean the area around the urethra. The collection bags have an adhesive label on one end that can be attached to the skin. On males, the entire penis should be placed in the bag. On females, the bag should be attached around the labia.
Check your child’s diaper frequently to see if urine has collected in the bag. Pour any urine into the container you were given. Cap this container and place it in the refrigerator between collections.
Collect all of the child’s urine for a 24-hour period. Use a new bag after each diaper change. Return the urine sample to your doctor or lab, as instructed.