Sodium (Na) in Urine
There is no chance for problems in collecting a
one-time or 24-hour urine sample.
A test for sodium in the urine is a
24-hour test or a one-time (spot) test that checks how much sodium is in the
urine. Sodium is both an
electrolyte and a mineral.
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 sodium 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:
- Taking medicines, such as birth control pills,
antibiotics, estrogens, tricyclic antidepressants,
nonsteroidal anti-inflammatory drugs (NSAIDs),
diuretics, lithium, and many medicines used to treat
high blood pressure.
- Having high levels of glucose,
- Getting sodium in intravenous
(IV) fluids given during a recent surgery or
What To Think About
- Sodium levels can also be measured in a blood
test. For more information, see the topic
Sodium (Na) in Blood.
- Doctors may look at
urine sodium and blood sodium levels to see whether conditions or medicines may
be causing fluid or electrolyte imbalances. Urine sodium levels are often high
when blood levels are low or low when blood levels are high. Urine sodium
levels are affected by medicines and hormones.
- To see whether the
body is passing too little or too much sodium in the urine, a value called the
fractional excretion of sodium (FENa) can be found by looking at the amounts of
sodium and creatinine in blood and urine. In a person with kidney failure, a
low FENa may mean less blood flow to the kidneys is causing the kidney
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
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.