Many patients are interested in the question - what is blood biochemistry, as well as residual nitrogen, decoding of blood tests. Biochemical analyzes are widely used in the diagnosis, they help to identify serious diseases, such as diabetes, cancerous tumors, various anemia, and to take timely measures in treatment. Residual nitrogen is present in urea, creatinine, amino acids, and indican. Its level may also indicate any pathological changes in the human body.
Blood chemistry
An indicative analysis of the biochemical composition of the blood allows with a high degree of probability to determine at an early stage various changes in tissues and organs. Preparation for biochemistry is carried out in the same way as with conventional blood tests. For research, blood sampling is performed from the ulnar vein. Important criteria are as follows:
• the presence of protein;
• nitrogenous fractions - residual nitrogen, creatinine, content of urea, inorganic compounds;
• bilirubin content;
• level of fat metabolism.
Residual blood nitrogen - what is it?
In conducting biochemical blood tests , the total content of blood substances in which nitrogen enters is evaluated only after all the proteins have already been extracted. The sum of the data is called the residual nitrogen of the blood. This indicator is recorded only after the proteins have been removed, for the reason that they have the most nitrogen in the human body. Thus, the residual nitrogen of urea, amino acids, creatinine, indican, uric acid, ammonia is determined. Nitrogen may also be contained in other substances of non-protein origin: peptides, bilirubin, and other compounds. Analysis of residual nitrogen gives an idea of the patient’s health, indicates chronic diseases, most often associated with problems of the excretory and filtering functions of the kidneys. Normal residual nitrogen is from 14.3 to 28.5 mmol / liter. An increase in this indicator occurs against the background of:
• polycystic;
• chronic kidney disease;
• hydronephrosis;
• stones in the ureter;
• tuberculous damage to the kidneys.
Diagnostics
Since the residual nitrogen sample is included in the biochemical analysis, preparation is carried out according to the same principles as before passing to other components of this diagnostic. To obtain more correct results, a number of rules must be observed when donating blood for biochemistry:
• If you have to take a reanalysis, it is best to do it in the same laboratory as the first time. Since all laboratories have their own diagnostic tests, they differ in systems for evaluating the result.
• A blood sample is taken from the ulnar vein, possibly from the finger, if there is no access to the vein or it is damaged.
• It is necessary to carry out the analysis on an empty stomach, not less than 9-12 hours after the last meal. You can drink water, but without gas.
• The ideal time for blood collection is considered to be 7-10 hours in the morning.
• Three days before the analysis, it is better to maintain the usual diet, you need to remove only fatty, spicy and fried.
• For three days it is necessary to exclude sports activities, especially if they are associated with body overloads.
• If you have to take an analysis for residual blood nitrogen, biochemistry requires cancellation of medication. This point must be discussed with your doctor.
• The results can be affected by stress, excitement, so at least half an hour before the samples you need to sit in a calm environment.
If the preparation for biochemistry was correct, then the test results will be more reliable. Decryption should only be done by medical professionals. Indicators often fluctuate relative to the standard, so they can be misinterpreted independently.
The rate of residual nitrogen in the blood
Normal readings in the blood of residual nitrogen fit into numbers from 14.3 to 26.8 mmol / L. It is worth noting that an increase in the indicator even to 30-36 mmol / l is not immediately interpreted as a manifestation of the pathology. Residual nitrogen, the norm of which is much less, can rise with the use of nitrogen-containing food, with dry food, and with a shortage of emergency substances. The jump in the indicator can also occur before childbirth, after intensive sports training and for a number of other reasons. That is why it is necessary to carefully prepare for the delivery of samples for blood chemistry. If the tests strikingly overestimate or underestimate the norm and at the same time there was proper preparation before blood sampling, this may indicate a number of diseases in the body.
The residual nitrogen fraction includes:
• urea nitrogen (46-60%);
• creatine (2.5-2.7%);
• nitrogen of amino acids (25%);
• uric acid (4%);
• creatinine (2.6-7.5%);
• other protein metabolism products.
Residual nitrogen is the difference between residual nitrogen and urea nitrogen. Here, the free fraction is represented by free amino acids.
Pathology
Pathologies of residual nitrogen include:
- hyperazotemia - when the level of residual nitrogen in the blood is too high;
- hypoazotemia - residual nitrogen in the blood is underestimated.
Hypoazotemia is most often observed with poor nutrition or in rare cases during pregnancy.
Hyperazotemia is divided into retention and production.
With retention hyperasotemia, violations of the excretory function of the kidneys occur, in this case, renal failure is diagnosed. The most common causes of the development of retention hyperasotemia are the following diseases:
• glomerulonephritis;
• pyelonephritis;
• hydronephrosis or renal tuberculosis;
• polycystic;
• nephropathy during pregnancy;
• arterial hypertension with the development of kidney disease;
• the presence of biological or mechanical obstacles to the outflow of urine (stones, sand, malignant or benign formations in the kidneys, urinary tract).
Production Hyperazotemia
Increased residual blood nitrogen may indicate production hyperazotemia when a pathological condition is accompanied by endogenous intoxication syndrome. Also observed with prolonged stress in the postoperative period. Production hyperazotemia is noted for infectious diseases that occur with fever when progressive tissue breakdown occurs, including diseases such as diphtheria, typhus, scarlet fever, and lobar pneumonia. Production hyperazotemia is characterized by an increase in the rate of residual nitrogen from the first day of the disease to the last manifestation of elevated temperature.
Relative can be observed with increased sweating, blood clotting, as well as profuse diarrhea, when the water balance is disturbed in the body.
Mixed Type Hyperasotemia
There are cases when the residual nitrogen is increased and mixed hyperazotemia is determined. It often occurs when poisoning with toxic substances: dichloroethane, mercury salts, and other dangerous compounds. The cause may be injuries associated with prolonged squeezing of tissues. In such cases, necrosis of the renal tissues may occur, while retention hyperazotemia begins with production. At the highest stage of hyperazotemia, residual nitrogen in some cases exceeds the norm by twenty times. Such indicators are recorded in extremely severe cases of kidney damage.
Indicators of residual nitrogen are overestimated not only with kidney damage. In Adisson's disease (adrenal gland dysfunction), the norms are also exceeded. This also happens with heart failure, with burns of a high degree of severity, with dehydration, with severe infections of a bacterial nature, with severe stress and with gastric bleeding.
Cure
It is possible to eliminate the manifestations of increased residual nitrogen by discovering the cause of this condition in time. For further treatment, the doctor should prescribe a number of additional studies, according to the results of which he will make a conclusion, establish the correct diagnosis and prescribe the necessary medication or other treatment. In order to detect the disease in time and cure it, it is necessary to undergo examinations in time and take all the tests. If any pathology is discovered, the correct treatment will not allow complications to develop, the disease to become an exacerbation and a chronic form.