Biochemical analysis of blood is a comprehensive laboratory diagnosis, conducted to assess the condition of internal organs and systems and to identify the body’s need for trace elements and its level of satisfaction. According to the biochemical parameters of blood composition, primary diagnostics of the functioning of the liver, kidneys, pancreas, and other organs are carried out, data is obtained on metabolic processes (lipid, protein, carbohydrate metabolism).
- Preparing for biochemistry analysis: how not to distort the results
- Average values of indicators: norm for adults
- Total protein and fractions
- Protein fractions
- Nitrogen metabolism
- Causes of fluctuations in the level of nitrogenous compounds
- Blood Carbohydrates
- Causes of Glucose Change
- Pigments in the LHC
- Bilirubin as an indicator of jaundice
- When is an analysis of bilirubin fractions assigned?
- Lipid Spectrum Analysis
- Cholesterol Estimate
- Causes of lipid metabolism
- Enzyme Analysis
- Hepatic Assay
- Alpha-amylase and pancreatic amylase
- Creatine Kinase and Its Fractions
- Phosphatase types and their diagnostic value
- Electrolyte Level
- Potassium in the blood
A comprehensive biochemical blood test (BAC) is recommended for prophylactic purposes to monitor the health and early diagnosis of diseases each year, as well as developing somatic or infectious diseases, during the course of the disease and during the clinical recovery phase.
The interpretation of the results of biochemical analysis is carried out by a specialist on the basis of laboratory norms and their compliance with the identified indicators. Self-deciphering of the tests most often provides an extremely superficial idea of the state of health and can cause incorrect self-diagnostics and subsequent self-treatment, as when interpreting the results it is necessary to take into account not only the age and sex indicators, but also the influence of existing and past diseases, taking certain medications that can affect the composition of the blood, and also to consider the picture of the analysis in the complex: many indicators indicate the presence of various processes, like both physiological and pathological, and only a specialist can correctly interpret the reason for the change in blood composition. Moreover, doctors often prescribe additional tests to diagnose after a blood test with this method in order to clarify and differentiate the causes of the patient’s identified condition.
Preparing for biochemistry analysis: how not to distort the results
For analysis of biochemistry, venous blood is used, about 5 ml distributed in several test tubes. Since the study includes indicators that can change due to the ingestion of food, water, physical activity or neuro-emotional arousal, as well as due to the intake of certain medications, there are rules for preparing for blood donation for the study. These include:
- hunger for 10-12 hours before blood collection;
- exclusion from the ration in the second half of the day before the analysis of coffee, brewed tea;
- a sparing diet for 2-3 days before testing: it is advisable not to eat fatty, fried, spicy foods, alcohol, etc.;
- during the previous day, it is necessary to avoid high physical activity and thermal procedures (bath, sauna, long hot bath);
- You need to donate blood before taking daily medications, conducting additional medical procedures and manipulations (injections, intravenous administration of drugs, physical studies – X-ray, fluorography, etc., visits to the dentist);
- On the day of blood sampling, you must refrain from physical activity, morning jogging or a long walk to the laboratory. Any physical activity affects the blood picture and makes it difficult to interpret the results;
- <a href how emotional arousal can also distort results;
- Immediately before the analysis, you should sit quietly for 10 minutes and make sure that the rhythm of breathing and heartbeat is normal;
- For accurate indicators of glucose analysis, one of the factors determined in biochemistry, especially important in the diagnosis of diabetes, one should refrain not only from morning drinks (including water) and chewing gum, but also from brushing teeth, especially with toothpaste . Taste receptors help to activate the pancreas and insulin production;
- one day before the analysis it is not recommended to take hormonal, diuretic, antibacterial, thrombo-absorbing drugs, drugs affecting blood viscosity, etc.,
- if it is necessary to diagnose the amount of cholesterol in the blood against the background of statin administration, the course of therapy (as agreed with the specialist) should be stopped within 10-14 days;
- if re-examination is required to clarify the results, blood should be taken with the most similar conditions: the same laboratory, time of day, up to the route from home to the place of blood collection (on foot or by transport).
Any human activity is caused by biochemical processes in the body and, accordingly, causes changes in the composition of the blood. The norms that experts are guided by in deciphering analyzes are based on the study of the influence of averaging factors – blood is taken on an empty stomach, at rest, without prior active actions and activating the digestive system. Abrupt changes in the composition of the blood will be noticeable even with distorted jogging behind the bus or morning cup of coffee indicators, however, slightly exceeding the limit of the norm or approaching it, indicating the development of the disease, may change due to non-compliance with the rules of preparation for the analysis of biochemistry and lead to inaccurate and unreliable interpretation .
Average values of indicators: norm for adults
The range of the norm of the amount of various substances contained in the blood is based on a study of the statistical indicators of the study of healthy people and patients with various diseases and pathologies. When interpreting, it should be remembered that standards standards differ depending on age, for some components there are specific standards for men and women. Under physiological conditions (for example, pregnancy) the limits of the norm also shift: thus, the amount of cholesterol in the gestational period may be twice as high as the conditional norm, and the hemoglobin at a certain period of gestation decreases due to an increase in blood volume, and this is considered normal, and not an indication for therapy.
To take into account the influence of various factors when interpreting the results, it is recommended to contact a specialist who assesses the patient’s general history and a complex blood picture, and not just the results of the indicator compliance with the norms in the table. Doctors evaluate the general symptoms, complaints, features of professional activity, the presence in the history of diseases and genetic propensities.
When evaluating the results, it is necessary to focus on the norms used in a particular laboratory, since different laboratory equipment can estimate the amount of certain substances in different units of measurement – micrograms, mmol per liter, percentage, etc. It is especially important to take into account these data interpretations of liver enzymes (alanine transferase, aspartate aminotransferase), where the temperature is also affected by the incubation temperature of the sample, which is usually indicated on the results sheet.
Some of the normal values for adults are shown in the table.
|Metric||Unit of Calculation||Valid Values ||Notes|
|Protein Total||Grams per liter||64-86||In children under 15, age norm values are lower|
|Albumin||Grams per liter or percentage to total protein||35-50 g / l
|Separate norms apply for children|
|Transferrin||Grams per liter||2-4||During pregnancy, rates rise, in old age they decrease|
|Ferritin||micrograms per liter||Men: 20-250
|For adult men and women, the norms are different|
|Micromoles per liter||8.6-20.5
|Separate indicators for children|
|Alpha-fetoprotein||unit per ml||0||Perhaps physiologically due to the appearance of a factor in the 2-3 trimester of gestation|
|Rheumatoid Factor||unit per ml||0-10||Regardless of age and sex characteristics|
In the detailed biochemical analysis of blood, there can be a lot of different indicators, both recommended for regular preventive research, and specific, studied in case of suspicion of specific diseases and disorders. In the detailed biochemistry, including the maximum number of studies, there is no need for analysis for the purposes of preventive examination, as well as for individual complaints and symptoms. Additional to the general indicators of research indicators of the components depend on the patient’s health: for example, with complaints of increased thirst, the focus will be on the amount of glucose in the blood; serum iron binding capacity), with signs of impaired liver function or the likelihood of developing hepatitis — hepatic enzymes (AST, ALT), bilirubin and alkaline phosphatase indicators.
Total protein and fractions
In the results of a clinical study and the LHC of the total chemical composition (total cholesterol) of the blood, the amount of total protein and its fractions – proteins is always estimated. In general, the blood contains more than 160 different proteins, combined in accordance with the composition and functions of three protein fractions: albumin, globulin (four types) and fibrinogen.
All proteins are important for the effective functioning of the body. The main organ responsible for the production of proteins is the liver, and the amount of protein reduced relative to the norm reflects the inability of the liver to synthesize proteins. This dysfunction may be associated with both diseases of the organ, and with other conditions and factors, among which are the effects of the following:
- low-protein diet (vegetarianism, fasting, eating habits with protein food restrictions);
- parasitosis (mostly helminthic invasions);
- blood loss (heavy discharge during menstruation, internal and external bleeding in diseases and injuries);
- extensive skin burns;
- Excess urinary protein excretion for kidney disease, proteinuria of the gestational period, etc.
- low protein synthesis in liver diseases (hepatitis, cirrhosis);
- long-term courses of therapy with glucocorticosteroids;
- development of tumor formations (malignant tumors of the bladder, stomach);
- low nutrient absorption in the intestines with enteritis, colitis, pancreatitis, celiac disease;
- diseases and pathologies of the structure, accompanied by accumulation of plasma (ascites, pleurisy, pericarditis).
Albumin concentration indicators are used in the diagnosis of pathologies of parenchymal organs, detection of rheumatism, signs of the development of tumors, the effect of hormonal drugs on the body and the effects of fasting and diet.
At the same time, reduced albumin fraction may indicate the development of nephrotic syndrome, hepatic or renal failure, tumors of the digestive system, tissue breakdown processes, cardiospasm, lymphorrhea, paracentesis, exhaustion, etc.
Urea, creatinine, uric acid, residual nitrogen, ammonia, and some other blood components are low-molecular nitrogenous substances. In the basic LHC, the values of urea and creatinine are examined, adding additional studies if there are suspicions of various disorders and pathologies.
Causes of fluctuations in the level of nitrogenous compounds
Nitrogenous compounds are produced by the breakdown of cells and tissues, a process inevitably accompanying the normal functioning of living organisms. Values that go beyond the normal values most often indicate a violation of the functions of the liver (where nitrogenous substances are synthesized during decomposition), kidneys (if there are accumulations of compounds in the body due to decreased filtration and impaired output from the urine) or increased protein breakdown by order or other reasons.
|Connection Name||As indicated by abnormality|
|Urea||Renal, hepatic failure, arterial hypertension, long-term squeezing syndrome, exposure to toxic substances|
|Creatinine||Severe lesions and pathologies of parenchymatous organs, adrenal dysfunction, tumors, diabetes mellitus|
|Uric acid||Gouty syndrome, leukemia, anemia with vitamin B12 deficiency, poisoning, dermatitis, acute infectious process, liver disease|
A decrease in the amount of nitrogenous compounds is registered with polyuria, liver failure, hypothyroidism, metabolic disorders, prolonged fasting, and also after hemodialysis procedures and the intravenous administration of glucose solution.
The main marker of carbohydrate metabolism in the body is glucose (aka “sugar”). Most people know that its high content signals the presence of diabetes or a pre-diabetic condition. However, the reason for the change in the glucose level can also be injuries, burns, a craze for sweets, violations of the rules of preparation for the analysis. In addition to these obvious causes, elevated glucose levels can occur with pancreatic diseases and liver pathologies.
In addition to glucose, detection of carbohydrate metabolism disorders is used to estimate the amount of glycated (or glycosylated) proteins: fructosamine (glycated albumin), glycosylated hemoglobin, glycated lipoprotein.
Causes of Glucose Change
Hypoglycemia is diagnosed at low glucose levels and hyperglycemia at elevated levels.
|Possible causes of hypoglycemia||Possible causes of hyperglycemia|
|Malnutrition, Diet, Fasting||Diabetes mellitus type 1, 2|
|Diseases of the digestive tract, preventing the absorption of carbohydrates (colitis, enteritis, etc.)||Injuries, brain neoplasms (often pituitary)|
|Hypothyroidism||Tumors, pathologies of the adrenal cortex|
|Liver Pathology||Thyrotoxicosis, pathologies of the thyroid gland|
|Long-term uncontrolled intake of insulin-containing drugs, hypoglycemic drugs||Epileptic syndrome|
|Encephalitis, meningoencephalitis, meningitis||Increased excitability, unstable psycho-emotional state|
|Insufficiency of the adrenal cortex function||Long-term treatment with glucocorticosteroids|
Pigments in the LHC
Some types of proteins have a specific color, most often due to the combination with metals (iron, copper, chromium). When they decay, bilirubin is released into the blood in an indirect or free form. In subsequent processes, it is converted into a related form. When assessing blood parameters, three types of hemoglobinogenic pigment are distinguished: total bilirubin, the amount of direct (bound, conjugated) bilirubin and the level of indirect (free, unbound, unconjugated). All three indicators are important and may indicate the presence of diseases and pathologies. Particular attention is primarily paid to free bilirubin, as it is toxic to the body.
Diseases that trigger the growth of pigment in the blood, are different – from genetic pathologies to the effects of blood transfusion and transplantation of organs and tissues to the recipient. Diagnosis is based on the ratio of bilirubin fractions. In most cases, exceeding the norm means the presence of liver disease and / or pathologies of the biliary tract.
Bilirubin as an indicator of jaundice
After passing the chain of changes in the liver and gall bladder, bilirubin enters the intestine, where the urobilinogenic compound is converted – the pigment, which removes urine and feces from the body.
With insufficient functioning of the liver or gallbladder, pathologies and disorders of the biliary tract, a significant part of bilirubin remains in the body, where, spreading through the tissues, gives them a yellow color. Because of this symptom, the name “jaundice” appeared, mistakenly associated exclusively with hepatitis A. However, in medical practice there are three types of processes that provoke the development of jaundice:
- toxic effects, poisoning, anemia of hemolytic etiology, pathological processes in the spleen, accompanied by its hyperfunction, accelerate the breakdown of pigment protein and increase the amount of unbound bilirubin to amounts that do not have time to be processed in the liver and accumulate in the blood and tissues;
- liver failure that occurs with hepatitis, cirrhosis, injuries, liver tumors, in which the body is not able to process the prescribed amount of bilirubin;
- for violations of the outflow of bile from the gallbladder, accompanied by squeezing of the biliary tract, bilirubin re-penetrates the bloodstream and then – into the tissue. This condition is registered with cholecystitis, gallstone disease, acute cholangitis, neoplasms that prevent the flow of bile, etc.
When is an analysis of bilirubin fractions assigned?
Indicators of total bilirubin are included in the standard set of BAC. A study on the level of fractions (conjugated and unbound bilirubin) is usually used in the presence of symptoms or diagnosed diseases: hepatitis of any etiology, liver cirrhosis, jaundice, etc.
Lipid Spectrum Analysis
Blood lipids (fats) make up the lipid spectrum. In the diagnostic biochemical test, the level of total cholesterol, low and high density lipoproteins (“bad” and “good” cholesterol), triglycerides is evaluated, and the atherogenic coefficient is calculated based on the ratio of components. In some cases, to clarify the diagnosis, an analysis of the number of phospholipids is carried out.
Normally, the indicator of total cholesterol in a healthy adult is within 3.0-5.2 mmol / l. From 40 to 60% of the total cholesterol is “good” cholesterol. What is it?
In the body, cholesterol is in two basic forms – high molecular weight with proteins and low molecular weight. High-density lipoproteins are mainly produced in the liver and are necessary for the body to participate in the formation of the cell membrane, regulation of hormonal processes, psycho-emotional state, etc.
Low (and very low) density lipoproteins mainly come from food. These compounds have the ability to accumulate in the blood vessels, forming cholesterol plaques (atherosclerosis). As a result of the formation of such an accumulation, the lumen of the vessel narrows, entailing a reduced blood supply to the organs and tissues. When lipoprotein aggregation is destroyed, its fragments are also dangerous, since they can contribute to the formation of blood clots.
Causes of lipid metabolism
|Increase total cholesterol||Lower Total Cholesterol|
|Nutrition disorders, obesity, diabetes mellitus, myocardial infarction, alcoholism, hypertension, gestational period, ischemia, gallstone disease, etc.||Liver diseases, hyperthyroidism, nutritional deficiencies, gastrointestinal diseases, lipid absorption, chronic obstructive pulmonary disease, rheumatoid arthritis|
Most often, the spectrum of enzymes in a biochemical test is limited to the analysis of “liver function tests,” AlT and AST, and amylase. An extended analysis may include a significantly wider list of enzymes.
Alaminoninotransferase (ALT) indicators mainly characterize the efficiency of the liver, but can also report disorders of skeletal muscle and cardiac muscle.
The study of asparto-aminotransferase (AST) is used in the diagnosis of diseases and pathologies of the liver, and is also used to identify cardiac pathologies (myocardial infarction, angina pectoris, rheumatic heart disease), and some inflammatory processes of infectious etiology.
Alpha-amylase and pancreatic amylase
This enzyme is responsible for the breakdown of complex carbohydrates. Both the increase and decrease in the concentration of amylase in relation to the norm have diagnostic value.
In most cases, the excess of the normal amount of amylase in the blood accompanies pancreatic diseases and pathologies. However, it can also be observed in hepatitis of viral etiology, endemic parotitis (“mumps”), renal failure, alcoholism, long courses of therapy with tetracycline drugs and glucocorticosteroids.
Decreased rates are noted in the following conditions and diseases:
- gestational toxicosis of the first trimester of pregnancy;
- myocardial infarction;
- necrotic processes in the pancreas.
Creatine Kinase and Its Fractions
The enzyme creatine kinase allows you to evaluate the effectiveness of energy metabolism in muscle tissue (MM fraction), cardiac muscle (MB) and brain tissue (VV). A diagnostic value is an increase in the concentration level of this enzyme, meaning an increased tissue breakdown. Thus, the subtype of creatine kinase MB is used, for example, in diagnosing the presence of myocardial infarction, assessing the extent of tissue damage and predicting the situation.
Lipase is responsible for the breakdown of neutral fats. Pancreatic lipase is recognized as a more valuable indicator for the diagnosis of pancreatic diseases than amylase, and is used to clarify the diagnosis and extent of organ damage.
Phosphatase types and their diagnostic value
There are two types of phosphatase: acidic (analysis of this enzyme is used in the differential diagnosis of diseases of the skeletal system, liver diseases, biliary duct pathologies) and alkaline, the change in the level of which occurs in most cases with prostate diseases.
Despite the fact that electrolytes in the blood are in a fairly small amount, a change in their concentration has a detrimental effect on the entire body and can be fatal. The main extracellular cation is sodium.
Sodium entering the body with food and liquids (sodium chloride – table salt), is responsible for the level of osmotic pressure in the tissues and the acid-base balance. Both elevated and decreased sodium in the blood can lead to minor changes in well-being, and, depending on concentration, to pathological conditions and coma.
Potassium in the blood
Electrolyte potassium is responsible for the conductivity of an electrical impulse in the heart muscle. Both excess of norm, and decrease in concentration of potassium can lead to a cardiac arrest.