Generality
Urea is the final product of protein metabolism; it is formed in the liver from ammonia, is released into the blood and readily filtered by the kidneys and eliminated in the urine.
Since urea synthesis is a continuous process, its levels in the blood stabilize around a very low but relatively constant value (roughly around 15-40 mg / dL).
- from the synthesis of ammonia (which in turn depends on the "dietary protein intake and the catabolism of tissue proteins),
- liver function
- renal function.
What's this
- Urea represents the main nitrogenous part of urine. Normally, this molecule is harmless to our body.
- Urea derives from the organic transformation of ammonia. This last substance is produced following the metabolism of amino acids (basic substances of proteins that contribute to the construction of organic tissues).
- Urea is transformed in the liver and released into the bloodstream, only to be eliminated in the urine, after being filtered through the kidneys.
- The level of urea in the blood depends on the functioning of the kidneys, the amount of protein introduced with the diet and the level of hydration.
Because it is measured
Urea accounts for about 90% of adult urinary nitrogen.
The measurement of its level in the blood allows to highlight the increase, which generally indicates an alteration of the renal function.
Uremia is a serious condition in which toxic nitrogen compounds (ie waste products of protein metabolism, normally excreted in the urine) are present in the blood in high concentrations. This pathological phenomenon is usually attributable to an insufficiency renal.
The dosage of urea in the blood is indicated in the presence of:
- Non-specific malaise;
- Signs or symptoms that lead to suspicion of some kidney disorder;
- Chronic diseases such as diabetes and heart failure.
In addition, the examination can be prescribed by the doctor in order to:
- Assess whether the kidneys are functioning before starting certain drug therapies;
- Monitor the effectiveness of dialysis or other treatments in patients with chronic and acute kidney disease.
Normal values
The amount of urea that can be measured in the blood should be approximately between 18-45 mg / dl (milligrams per deciliter) in men and 15-42 mg / dl in women.
Values other than the reference ones indicate an "imperfect purification of the blood by the kidneys.
Uremia Alta - Causes
For further information: Uremia - Causes and Symptoms
High blood levels of urea occur as a result of excessive nitrogen intake, as occurs in people who follow a high-protein diet.
The condition is also common in cases of increased protein catabolism and tissue damage, as occurs in the presence of:
- Hyperthyroidism;
- Prolonged fasting;
- Severe infections;
- Neoplasms;
- Significantly strenuous or intense sports or work activity.
A high level of urea in the blood can also result from:
- Gastrointestinal bleeding (peptic ulcer);
- Addison's disease;
- Trauma;
- Kidney failure.
This latter condition can be caused by organ damage - resulting for example from diabetes or hypertension - but also by an obstruction of the urinary tract, for example due to the presence of a kidney stone or a tumor.
An insufficient blood supply to the kidneys, typical of dehydration, burns, bleeding and heart failure, can also increase serum urea levels.
Low Uremia - Causes
Low blood urea levels are uncommon and usually not a concern. Generally, they occur following an insufficient supply of nitrogen, typical of:
- Low protein diets;
- Alcoholism;
- Malnutrition;
- Malabsorption diseases.
Other conditions characterized by the drop in plasma urea levels are:
- States of hyperhydration (excessive fluid intake);
- Pregnancy;
- Severe liver disease with organ damage;
- Simmonds disease (panhypopituitarism).
However, blood urea levels are not measured for the purpose of diagnosing or monitoring such conditions.
How it is measured
The evaluation of urea is carried out by means of a simple blood test, usually taken at the crease of the elbow.
Preparation
The collection is usually done in the morning. Your doctor will suggest if you need to fast.
For a correct interpretation of the results it must be borne in mind that the values of this analysis can be influenced by some particular conditions, such as, for example, dehydration and the amount of protein present in the diet.
Interpretation of Results
- Blood urea may increase mainly in the presence of decreased kidney function. This may be due to high protein diets, dehydration, heart failure, acute or chronic kidney disease, and drug therapy with toxic action on the kidneys.
- A decrease in urea values can be determined, however, by diets that are too low in proteins or carbohydrates, prolonged fasting, states of malnutrition, liver failure, poisoning and nephrosis.
