Urea is created in the liver as a product of protein degradation. The body is unable to use urea, which is why it is transferred to the kidneys via blood and removed in urine. The amount of urea in the blood does not increase unless the kidneys are considerably dysfunctional. Therefore, urea is not the primary indicator for renal functions. Healthy kidneys remove more than 90% of the urea produced by the body. The rest of the urea is secreted through the skin and the digestive tract.
The urea levels in the blood depend on:
- The status of the liver
- The protein content of the diet
- The state of nutrition
- Renal flow
- Protein degradation
When should urea be measured?
Many disorders affecting the liver and the kidneys also affect the levels of urea in the blood. The urea levels increase when the liver produces more urea or lower amounts of urea are removed from the kidneys. In the event of liver damage, the urea levels decrease as the liver no longer produces it normally.
Urea levels can be checked in connection with the following symptoms:
- Impaired concentration
- Loss of appetite
- Poor sleep quality
- Swelling (around the eyes, wrists, ankles and the abdomen)
- Reduced amount of urine
- Foamy, brownish urine
- Difficulty urinating (burning sensation, increased urinating frequency)
- High blood pressure
What does a urea test measure?
Urea and creatinine (S-Krea) values are used to measure renal function and monitor those suffering from a kidney disease.
Urea levels can be tested in connection with the following conditions:
- When monitoring the progress of a kidney disease
- When analysing protein metabolism
- When monitoring renal function in connection with the use of certain medicinal products
How do I interpret the test result (fS-Urea)?
- Women under 50 y: 2,6 – 6,4 mmol/l
- Women over 50 y: 3,1 – 7,9 mmol/l
- Men under 50 y: 3,2 – 8,1 mmol/l
- Men over 50 y: 3,5 – 8,1 mmol/l
The urea levels increase with age and depend on the amount of protein in the diet. Protein-rich food increases the blood’s urea levels. A low-protein diet, in turn, decreases urea levels. Newborns and young children have lower urea levels.
Creatinine and urea tests are used when analysing the kidneys’ capacity for processing waste products. Sodium (S-Na), potassium (S-K) and calcium (S-Ca) can also be tested when analysing renal function.
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
Read more about defining reference values.
What can cause elevated urea values?
High urea levels indicate poor renal function. This may be caused by for example:
- Weakened renal blood flow
- Heart failure
- Recent heart attack
- Severe burns
- Gastrointestinal bleeding
- Obstructed urine flow
- Dehydration of the body
- Protein-rich diet
What can cause decreased urea values?
Low urea levels are rare but may occur in the following conditions:
- Use of diuretics
- Use of growth hormones and anabolic steroids
- Liver dysfunction
- Low-protein diet
- Infusion (intravenous drip)
The most typical additional tests
- Potassium is one of the most important minerals in the blood (2001 S-K)
- In addition to potassium, sodium is one of the most important minerals in the body (2382 S-Na)
- Creatinine indicates kidney function (2143 S-Krea)
- Filtration rate of the glomeruli is a precise indicator of renal function (6354 Pt-GFRe)
- Calcium is critical for all cells of the body (2013 S-Ca, 6032 S-Ca-Albk)
SYNLAB test list: Urea (2888 fS-Urea) https://www2.synlab.fi/laboratoriokasikirja/tutkimuskuvaukset/urea/
Terveyskirjasto health library: Urea (P-Urea) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=snk03122&p_hakusana=urea
Lab Test online: Urea test https://labtestsonline.org.uk/tests/urea-test
Fasting is required
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