Urea, urea nitrogen – test, standards. Reduced and increased urea concentration

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Urea is the end product of protein metabolism in the body and as such is an indicator of kidney function. It is also an organic chemical that is excreted in urine and sweat. It is produced mainly in the liver.

Urea concentration – what does it show?

Urea is mainly produced in the liver. Serum urea concentration allows you to determine whether the kidneys are fulfilling their excretory function (suspected renal failure). For the test to be unambiguous and reliable, it should be combined with the measurement of creatinine (the ratio of urea to creatinine in the blood serum). Unfortunately, the assessment of glomerular filtration through the determination of urea is difficult, as its level depends on many factors.

Your doctor may refer you to a urea index test when you complain of drowsiness, fatigue, vomiting and coagulation disorders (may mean uremia). Thanks to the examination, it is also possible to determine whether a given patient has catabolic states and dehydration. Such conditions may arise after treatment with cytostatics or due to the use of radiation. Advanced liver failure is a very rare cause of urea reduction.

You can purchase a prophylactic examination package – blood tests, in which the medium and maximum variants include, among others, urea index study.

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Urea – when do we perform the test?

Your doctor may suggest urea testing in the following situations.

1. Suspicion of kidney dysfunction.
2. Diagnostics of excess nitrogen compounds in the body.
3. Control of catabolic and anabolic processes.
4. The occurrence of ailments in the patient in the form of: drowsiness, disturbance of consciousness, vomiting, fatigue, itching of the skin or coagulation disorders. These symptoms may suggest uremia.
5. Assessment of the degree of urea poisoning and the effectiveness of dialysis therapy.

Usually, creatinine is tested along with urea, which is a better indicator of kidney function. Both parameters make it possible to distinguish between renal and prerenal causes of increased amounts of nitrogen compounds.

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Urea – urea concentration test

Urea concentration is tested by taking blood from a vein in the arm once. The test material is serum. The patient should be fasting for at least eight hours.

Note: Do not use ammonium heparin as a preservative as the ammonia contained in it will distort the result.

Waiting time for the urea result: 1 Day.

The blood urea level depends on:

1. the amount of protein in the diet,
2. liver function,
3. the degree of protein breakdown,

For this reason, the results should be analyzed together with the information collected during the medical interview.

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Urea concentration test – urea standards

The appropriate standard of urea concentration is: 2,5-6,7 mmol / l (15-40 mg / dl). Urea in the form of nitrogen urea (BUN) has different standards. The reference value for urea nitrogen is 7-18 mg / dl. Urea is one of the final, major products of protein metabolism, and its blood levels increase with age.

Do you have kidney problems? Make an e-appointment with a nephrologist today and consult any disturbing symptoms.

Urea concentration test – interpretation

Urea should be interpreted based on the norms. The amount of urea in the blood depends on its production (only in the liver) and its renal excretion. In the elderly, the concentration of urea in the blood is higher. Urea nitrogen is labeled BUN.

Urea test results should be interpreted based on the norm. They are given indicative and therefore cannot be used as the basis for a diagnosis. Each laboratory sets its own limits of standards, therefore the parameters may slightly differ from each other. When determining urea in the blood serum, also ammonia and creatinine should be determined and an ultrasound examination of the kidneys should be performed. Only after interpreting all these results is it possible to establish the cause of the abnormal blood urea concentration.

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Increased urea concentration

The cause of high urea levels can be:

1. dehydration,
2. Burns,
3. renal excretory impairment,
4. gastrointestinal bleeding
5. kidney failure
6. non-renal failure of the kidneys (e.g., obstruction of the ureters)
7. tumors,
8. injuries,
9. high protein content in the diet,
10. catabolism in the case of chemotherapy, hyperthyroidism and the use of glucocorticoids.

Increased urea concentration in the blood requires medical consultation. The same is true for people already diagnosed with chronic kidney disease.

High urea concentration it usually occurs during oliguria or anuria (high concentrations are also accompanied by blood in the urine, pain when urinating, fatigue and sleep problems, increased blood pressure, numbness in the limbs, itching of the skin and muscle spasms).

However, it should be remembered that high urea concentration does not have to be a symptom of a disease state, and it often occurs in people who maintain a high-protein diet and in people who are severely dehydrated. In addition, it should be added that some pharmacological compounds, such as antiprotozoal, antitumor and anti-infective drugs, may be responsible for the increased level of urea in the blood.

When the concentration of urea is elevated, it is worth using the Cleansing Kit, which includes: beetroot juice, Cleansing tea and nettle seed oil. The products included in the set include support the body in the excretion of urea from it.

Blood tests – how to read their results

Lowered urea concentration

Low levels of urea are very common in children because of their predominance of anabolic processes. The cause of the low concentration may also be polyuria, i.e. a disease characterized by increased urine output (over 2,5-3l per day). Low levels can also indicate kidney damage.

Low blood urea levels may be a symptom of a low-protein diet. This condition is characteristic of malnourished people, people with malabsorption disorders and sick people.

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Ways to lower blood urea

One way to lower the urea level in the blood is by dialysis. This treatment involves, among other things, the removal of urea nitrogen from the patient’s body. Although it is a very effective method, it is considered symptomatic treatment.

Another way to lower blood urea levels is a low-protein diet. but it cannot contain less than 20 g of protein per day, otherwise it could not provide the right amount of amino acids during the day. It is very important that the ingredients of the diet are carefully selected. Protein is limited to 0,6–0,7 g / kg body weight per day.

Products that are characterized by a low protein content include: jam, marmalade, mild sauces, butter, low-protein flour pasta, low-protein bread, jelly and potatoes. It is not recommended to eat, for example, smoked fish, cheese and dairy products, cold meats, canned food, pickled products and legumes.

In the event of a low blood urea concentration, various nutritional supplements with increased protein content available from pharmacies can help.

BUN (urea nitrogen) in patients with heart failure

Heart failure is one of the leading causes of hospitalization and mortality. Some patients are at high risk of short- and long-term mortality after first admission with acute decompensated heart failure. These patients should be identified, closely monitored and treated. Blood urea nitrogen (BUN) on admission has been observed to be a predictive indicator of short-term mortality.

Recently, it has been shown that higher BUN levels at discharge are also a poor prognosis. Specialists tried to investigate the effect of variability in urea nitrogen concentration during hospitalization on mortality.

A retrospective study included patients with first hospitalization with a primary diagnosis of heart failure. Patients were divided into four groups based on their BUN values ​​at admission and discharge, respectively: normal-normal, elevated-normal, normal-elevated, and elevated-elevated.

Four thousand seven hundred sixty-eight patients were included; 2567 are men (53,8%); the mean age was 74,7 ± 12,7 years. The 90-day mortality rate in the normal-normal group was 7% lower than in the elevated-normal (14,6%) and elevated-normal (19,3%) groups. The 90-day mortality in the group with the increased level (28,8%) was significantly higher than in the other groups. These results were retained during the 36-month follow-up period.

When BUN levels were broken down to <30, 30–39, and> 40 mg / dL, higher BUN levels correlated with higher 90-day mortality, regardless of creatinine, brain natriuretic peptide levels, or age. Moreover, BUN on admission and discharge correlated better with mortality than creatinine and the glomerular filtration rate at the same points.

This study showed that BUN is a predictor of short-term (90-day) and long-term mortality (up to 36 months) in patients first onset of acute heart failure. BUN both on admission and on discharge showed correlation with 90-day mortality and mortality for the first 36 months after admission; however, the worst prognosis was observed in patients with elevated blood urea nitrogen levels at both admission and discharge.

The results show that a poorer prognosis is observed if concentration levels worsen or even do not improve during a hospital stay, regardless of BUN admission levels: patients with normal blood urea nitrogen levels on admission have a worse prognosis if discharged with increased levels compared to normal levels after discharge; also, patients with elevated levels on admission have a poorer prognosis if they are discharged with increased levels compared to normal levels at discharge. In the case of short-term prognoses, worse variability of blood urea nitrogen concentration correlates with a worse prognosis.

If you are concerned about your health, do some basic blood and urine tests. Check if worrying symptoms do not indicate kidney stones.

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