Test Overview
A test
for potassium in the urine is a 24-hour test or a one-time (spot) test that
checks how much potassium is in the urine. Potassium is both an
electrolyte and a mineral. It helps keep the water
(the amount of fluid inside and outside the body's cells) and electrolyte
balance of the body. Potassium is also important in how nerves and muscles
work.
Potassium levels often change with sodium levels. When
sodium levels go up, potassium levels go down, and when sodium levels go down,
potassium levels go up. Potassium levels are also affected by a hormone called
aldosterone, which is made by the
adrenal glands.
Potassium levels can be
affected by how the
kidneys are working, the blood
pH, the amount of potassium you eat, the
hormone levels in your body, severe vomiting, and
taking certain medicines, including potassium supplements. Certain cancer
treatments that destroy cancer cells can also make potassium levels
high.
Many foods are rich in potassium, including scallops,
potatoes, figs, bananas, prune juice, orange juice, and squash. A balanced diet
has enough potassium for the body's needs. But potassium is passed in the urine
even if the level in the body is low, so the level of potassium can get
lower.
A potassium level that is too high or too low can be
serious. Abnormal potassium levels may cause symptoms such as muscle cramps or
weakness, nausea, diarrhea, frequent urination,
dehydration, low blood pressure, confusion,
irritability, paralysis, and changes in heart rhythm.
Why It Is Done
A urine test to check potassium levels
is done to:
- Check levels in people being treated with
medicines, such as
diuretics and for people having
kidney dialysis.
- Check how well the
kidneys are working.
- Check to see whether treatment for low or high
potassium levels is working.
- Check people with
high blood pressure who may have a problem with their
kidneys or adrenal glands.
- Check the effects of extra nutrition
(total parenteral nutrition [TPN]) on potassium
levels.
- Check to see whether certain cancer treatments are causing
too many cells to be destroyed (cell lysis). Cell lysis syndrome causes very
high levels of some electrolytes, including potassium.
How To Prepare
You do not need to do anything before
having this test.
Talk to your doctor about any
concerns you have regarding the need for the test, its risks, how it will be
done, or what the results will mean. To help you understand the importance
of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
Urine potassium can be checked in a
single urine sample but it is more often measured in a 24-hour urine
sample.
Clean-catch midstream one-time urine collection
- Wash your hands to make sure they are clean
before collecting the urine.
- If the collection cup has a lid,
remove it carefully and set it down with the inner surface up. Do not touch the
inside of the cup with your fingers.
- Clean the area around your
genitals.
- A man should retract the foreskin, if
present, and clean the head of his penis with medicated towelettes or
swabs.
- A woman should spread open the genital folds of skin with
one hand. Then use her other hand to clean the area around the
urethra with medicated towelettes or swabs. She should
wipe the area from front to back so bacteria from the
anus is not wiped across the urethra.
- Begin urinating into the toilet or urinal. A
woman should hold apart the genital folds of skin while she
urinates.
- After the urine has flowed for several seconds, place the
collection cup into the urine stream and collect about
2 fl oz (60 mL) of this
"midstream" urine without stopping your flow of urine.
- Do not
touch the rim of the cup to your genital area. Do not get toilet paper, pubic
hair, stool (feces), menstrual blood, or anything else in the urine
sample.
- Finish urinating into the toilet or
urinal.
- Carefully replace and tighten the lid on the cup then
return it to the lab. If you are collecting the urine at home and cannot get it
to the lab in an hour, refrigerate it.
Urine collection over 24 hours
- You start collecting your urine in the
morning. When you first get up, empty your bladder but do not save this urine.
Write down the time that you urinated to mark the beginning of your 24-hour
collection period.
- For the next 24 hours, collect all your urine.
Your doctor or lab will usually provide you with a large container that holds
about 1 gal (4 L). The container has a small amount of preservative in it.
Urinate into a small, clean container and then pour the urine into the large
container. Do not touch the inside of either container with your
fingers.
- Keep the large container in the refrigerator for the 24
hours.
- Empty your bladder for the final time at or just before the
end of the 24-hour period. Add this urine to the large container and record the
time.
- Do not get toilet paper, pubic hair, stool (feces), menstrual
blood, or other foreign matter in the urine sample.
How It Feels
There is no discomfort in collecting a
one-time or 24-hour urine sample.
Risks
There is no chance for problems in collecting a
one-time or 24-hour urine sample.
Results
A test for potassium in the urine is a
24-hour test or a one-time (spot) test that checks how much potassium is in the
urine. Potassium is both an
electrolyte and a mineral.
Normal
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Results are ready in 1 day.
Many conditions can affect potassium levels. Your doctor
will talk with you about any abnormal results that may be related to your
symptoms and past health.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
What To Think About
- Potassium levels can also be checked in a blood
test. For more information, see the topic
Potassium (K) in Blood.
- Doctors may look
at urine potassium and blood potassium levels to see whether conditions or
medicines may be causing fluid or electrolyte imbalances. Urine potassium
levels are often high when blood levels are low or low when blood levels are
high. Urine potassium levels are affected by medicines and hormones.
References
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.
- Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Credits
| By | Healthwise Staff |
|---|
| Primary Medical Reviewer | E. Gregory Thompson, MD - Internal Medicine |
|---|
| Specialist Medical Reviewer | Avery L. Seifert, MD - Urology |
|---|
| Last Revised | September 1, 2010 |
|---|
Seton is proud to have four hospitals – the only hospitals in Central Texas - that have earned the Magnet designation, the highest award for nursing excellence given by the American Nurses Association.