Potassium (k) test

A potassium test checks how much potassium is in your child's blood or urine. Potassium helps keep the body's water and electrolytes in balance. It's also important in how nerves and muscles work.

Your child can have a blood sample taken to test potassium levels. Or you can collect your child's urine. It can be checked in a single urine sample. But it's more often measured in a 24-hour urine sample.

A blood or urine test for potassium may be done to:

• Check how well your kidneys are working.
• Check levels if you are being treated with medicines such as diuretics or having kidney dialysis.
• See if treatment for low or high potassium levels is working.

Blood test

A health professional uses a needle to take a blood sample, usually from the arm.

Urine test

A urine test can be done using a single urine sample or urine collected over 24 hours. A single urine sample may be taken at a health professional's office or at home. A 24-hour sample is done at home.

• You don't need to do anything before your child has this test.
• For 24-hour urine collection, your doctor or lab will usually give you a large container that holds about 1 gallon.