Urea is a waste product from the breakdown of amino acids found in proteins. When protein is broken down in the liver, nitrogen is produced in the form of ammonia and is excreted in urine.
It is almost exclusively excreted from the body by the kidneys and its measurement in both urine and blood can help to identify kidney disease.
Many diseases of the kidney or liver can affect the amount of urea found in the blood. If the liver produces increased levels of urea or reduced amounts are removed by the kidneys then urea concentrations will be high.
Urea and creatine levels are both used to determine how well the kidneys are functioning.
When amino acids are broken down, the liver produces nitrogen in the form of ammonia. In the liver, nitrogen combines with other chemicals to produce urea which is a waste product. The urea then travels in the blood to the kidneys where it is filtered out of the blood and is excreted out of the body via the urine. If the kidneys are functioning normally, 90% of the urea produced by the body is removed. Hence, the blood urea levels can show how well the kidneys are working.
Urea levels can change if there is a disease present in the body. For example, high levels of urea in the body can be caused by reduced kidney function, commonly caused by kidney disease. However, urea is not an exclusive biomarker for kidney disease. Its levels can also indicate other conditions such as congestive heart failure, dehydration and stress.
Low levels of urea are less common that elevated levels and are rarely a cause for concern. Pregnant females may experience low urea levels, so too can individuals who are malnourished or who have liver disease.
If you are worried about your kidney function or just want to check where you fall on the range, you can test your urea level with Forth’s leading blood test service.
There are several causes of chronic kidney disease, including:
Diabetes is the most common cause of chronic kidney disease worldwide.
Kidney disease can cause many symptoms but can include:
Kidney function can be maintained and even improved by making some changes to your lifestyle. Research has shown reducing abdominal circumference in people with metabolic syndrome can improve estimated glomerular filtration rate (eGFR), another measure of kidney function. A greater waist to hip ratio can increase the risk of decreased filtration.
Diet is helpful in improving the health of the kidney, particularly the Mediterranean diet as this reduces the risk of developing chronic kidney disease as well as other medical conditions.  The diet has been linked to a lower risk of mortality and is characterised by a high intake of fruit, vegetables, legumes, nuts, cereals, and olive oil as well as a moderate intake of fish. The diet is low in meat, saturated fat and poultry.
Exercise is also fundamental in maintaining kidney health. In fact, studies have shown that individuals with cardiovascular disease and chronic kidney disease can improve their kidney function with exercise therapy. 
However, it is important to remember that chronic kidney disease is usually a result of another medical condition such as diabetes or high blood pressure. These types of condition can be prevented by making healthier lifestyle choices. For example, limiting salt intake and eating the correct amount of protein can help to prevent the onset of disease as well as cutting down on consuming bad fats like saturated and trans fats which are found in processed meats as well as cakes, biscuits and pastries. Drinking plenty of water daily is also essential for kidney health. Prolonged dehydration can damage the kidneys and affect their ability to filter the blood. Aim to drink approximately 2 litres of water per day and increase this if you are exercising or exposed to high temperatures.
 Higgins, C. (2016). Urea and the Clinical Value of Measuring Blood Urea Concentration. Available at: https://acutecaretesting.org/en/articles/urea-and-the-clinical-value-of-measuring-blood-urea-concentration
 Lab Tests Online UK. (2016). Urea Test. Available at: https://labtestsonline.org.uk/tests/urea-test
 NHS. (2016). Overview Chronic Kidney Disease. Available at: https://www.nhs.uk/conditions/kidney-disease/
 Jha, V et al. (2013). Chronic Kidney Disease: Global Dimension and Perspectives. The Lancet.
 Huang, X., Jiménez-Moleón and Lindholm, B et al., (2013). Mediterranean Diet, Kidney Function, and Mortality in Men with CKD. Clinical Journal of the American Society of Nephrology: 13(5).
 Toyama, K., Sugiyama, S and Oka, H et al., (2010). Exercise Therapy Correlates with Improving Renal Function Through Modifying Lipid Metabolism in Patients with Cardiovascular Disease and Chronic Kidney Disease. Journal of Cardiology: 56, pp 142-146.