What is urea?
Urea – also known as carbamide – is produced when protein building blocks (amino acids) are broken down in the liver. This initially produces toxic ammonia, which in higher concentrations damages the brain in particular. For this reason, the body converts most of the ammonia into non-toxic urea, which is then excreted via the kidneys and in small quantities in the stool and sweat.
When to determine urea?
Possible symptoms of elevated urea levels include fatigue, headache, fever, increased or decreased urination, or pain while doing so. Together with other parameters, an elevated urea concentration is an indication for renal replacement therapy and provides information about its effectiveness.
Urea reference values
Depending on age, the following blood urea standard values:
|
Age |
Urea normal value |
|
under 3 years |
11.0 – 36.0 mg/dl |
|
3 to 12 years |
15.0 – 36.0 mg/dl |
|
13 to 18 years |
18.0 – 45.0 mg/dl |
|
16.6 – 48.5 mg/dl |
When are urea levels too low?
Since urea is produced during the metabolism of amino acids, the most common reason is a lowered protein intake. If the body produces more protein (for example, in late pregnancy or childhood), low urea levels also occur. Liver damage should also be considered. Extremely rarely, enzyme defects in the urea cycle are responsible for low urea levels. They lead to death at an early age.
Elevated urea levels resulting from an increased intake of protein in the diet are much less dangerous. Elevated urea levels are also measured when the body is dehydrated.
Urea itself is nontoxic, but in high concentrations can cause headaches fatigue, vomiting, and severe tremors. Elevated levels of urea in the blood therefore always give reason for further diagnosis.
What to do if urea is elevated or decreased?
Far more relevant is an elevated urea level. Here, the cause should be found and remedied as quickly as possible. Kidney replacement procedures (dialysis) such as hemofiltration are used to acutely lower elevated blood urea levels. Such blood washing is indicated if the urea in the blood is more than 200 mg/dl.
