The hemogram, also known as a complete blood count (CBC), consists of a number of parameters, in which the various blood cells are counted and their indices are calculated.
The purpose of erythrocytes, or red blood cells, is to provide oxygen to tissues and organs.
Thrombocytes, or platelets, ensure normal blood clotting. Their main function is to ensure the integrity of the blood vessels after the vessel wall has been injured. Various chronic and acute bacterial and viral infections can cause an increase in platelet counts, called reactive thrombocytosis, which returns to normal at the end of the infection.
Leukocytes, or white blood cells, are cells of the body’s immune system. Their count can increase for a variety of reasons, such as infections, inflammation and blood diseases. Eating habits, stress, physical activity, smoking, a lack of oxygen and various medicinal products also contribute to the increase in the total leukocyte count.
White blood cells are divided into five subclasses:
1. Neutrophils
2. Monocytes
3. Lymphocytes
4. Eosinophils
5. Basophils
Neutrophils are among the first blood cells to respond to infection, and their numbers increase significantly and rapidly with infection. The degree of neutrophil elevation depends on the severity and type of infection. Decreased neutrophil counts, or neutropenia, increases the risk of contracting viral diseases; it also increases the risk of infections. The causes of neutropenia may include congenital or acquired vitamin B12 or folic acid deficiency, use of medications, alcohol abuse, severe infection, eating disorders, autoimmune diseases, and more.
Monocytes together with neutrophils are called phagocytes and their main function is to destroy (ingest, and sometimes digest) microorganisms and other foreign bodies. Circulating monocytes and neutrophils are able to migrate from the blood into tissues where they destroy bacterial and fungal pathogens, helping to fight infections.
Monocyte counts increase with various chronic inflammations and infections, medications, and several blood-borne diseases.
Lymphocytes produce antibodies and directly kill microbes. Elevated lymphocyte counts are common in acute viral diseases, including infectious mononucleosis (glandular fever) and pertussis, smoking, overactive thyroid and chronic lymphocytic leukaemia. Their number decreases in case of immunodeficiency syndromes, systemic connective tissue diseases and infections (tuberculosis, typhoid, sepsis).
Eosinophil counts increase in case of allergies, asthma, systemic connective tissue diseases, parasitic and tumoral diseases. Significant increase in eosinophil counts in the blood requires further investigation.
Basophils are involved in producing some of the symptoms caused by allergic reactions in the body. Their number increases in case of allergic conditions, chronic infections (e.g. tuberculosis), viral diseases (e.g. chickenpox, smallpox), inflammatory diseases (e.g. rheumatoid arthritis and ulcerative colitis), iron deficiency and tumoral diseases.

Inflammation is a protective reaction of the innate immune system. CRP is one of the best and most sensitive indicators of inflammation of liver cells in the early stages of inflammation. CRP helps to protect the organism from several pathogens.
The production and levels of CRP in the body increase relatively rapidly in response to inflammation and tissue damage, reaching a peak within 2 days, and they decrease rapidly when the disease goes into remission. CRP levels increase significantly in bacterial infections, thereby helping to differentiate between viral and bacterial infections.
CRP is also a marker of cardiovascular disease risk. Its levels increase with age and body mass index. High levels of CRP are not disease-specific, so further testing is needed to make a specific diagnosis.
CRP levels increase due to various diseases and conditions:
• acute and chronic inflammation
• infectious disease
• tissue damage
• metabolic syndrome
• tumoral processes
• acute pancreatitis
• post-surgery, burns
• leukaemia
• smoking
• obesity
• hormone replacement therapy
CRP levels are reduced by regular physical activity, healthy diet and weight loss, vitamin E administration, statins and non-steroidal anti-inflammatory drugs (NSAIDs).

Iron deficiency can cause a variety of health concerns and changes in our well-being. The most serious consequence is iron deficiency anaemia or simply anaemia, in which the total amount of red blood cells and/or haemoglobin in the blood has decreased.
Iron deficiency suppresses the immune system and increases the risk of diseases.
The causes of low ferritin levels can vary. Iron deficiency anaemia (characteristic low haemoglobin and red blood cell count) occurs in about 5% of the population, while the prevalence of iron deficiency is 3-4 times higher and indicates that the body’s iron stores have decreased. Typical symptoms of iron deficiency are fatigue, weakness, decreased exercise capacity, decreased ability to work, poor concentration, irritability, restless legs syndrome, loss of appetite, pale skin, brittle nails and hair, etc.
Ferritin is an acute-phase protein and its levels can increase for a variety of reasons, regardless of the status of iron stores. This makes it difficult to diagnose iron deficiency, as concomitant iron deficiency may be hidden. For example, iron levels can increase due to inflammation, liver diseases, excessive alcohol consumption, hereditary or acquired hemochromatosis (excessive intestinal absorption of dietary iron) or malignant tumours.
The traditional standard range of ferritin (10-12 µg/L) is not optimal in all cases to explain iron deficiency.
A serum ferritin level < 30 µg /L is the most sensitive and specific indicator of iron deficiency. Some patients with a restless legs syndrome have iron deficiency with ferritin levels < 75 (50) µg/L. A serum ferritin level > 100 µg/L generally rules out the possibility of iron deficiency anaemia.

Folate is essential for the normal metabolism of proteins, fats and carbohydrates as well as for haematopoiesis (formation of blood cellular components) and regeneration of cells.
Folate deficiency primarily affects haematopoiesis, mucous membranes, skin, bone tissue and the nervous system. Folate together with vitamin B12 is involved in homocysteine metabolism, positively affecting cardiovascular function.
Folate deficiency leads to anaemia, which may be accompanied by neuro-psychiatric and sensitivity disorders.
Folate is naturally present in a wide variety of foods; it is stored in the liver for up to 3 months. Folate is extremely sensitive to destruction by heat and decomposes quickly during cooking. Its absorption is reduced by smoking, alcohol, coffee, oral contraceptives, some medical products and chronic diseases.

Proteins are involved in the production of antibodies. They provide the body with a strong and functioning immune system that protects us against viruses and bacteria. They are also involved in the transport of compounds, such as oxygen, thyroid and other hormones, vitamins and minerals, medicinal products and more.
Consuming sufficient amounts of protein boosts our immune system and makes the body more resistant to disease. Proteins are also an important source of energy. A low-protein diet can cause weakness, fatigue and susceptibility to infections. Severe protein deficiency causes swelling and muscle weakness, hair and skin changes.
Low protein levels may indicate:
• decreased protein production due to liver diseases
• malnutrition or inadequate protein intake
• protein malabsorption
• “breakdown” of the protein by the body, which may be associated with fever, inflammation and malignant tumours
• kidney and gastrointestinal diseases
• excessive water consumption

Complements are proteins found in the blood and tissue fluids that are actively involved in the body’s immune system, supporting the functioning of antibodies. The activation of C3 and C4 ensures the normal immune response of the body. The components regulate inflammation, activate phagocytes, and kill bacteria and viruses.
The levels of C3 and C4 are reduced due to a number of diseases (e.g. rheumatic diseases, lupus (SLE)), where complement components are depleted when the immune system is activated and their low levels indicate autoimmune disease. The levels are also lower than normal in case of some liver diseases or various inherited defects.
Increased levels of complements occur in the acute phase of inflammation, especially in bacterial infections and chronic inflammations.

Complements are proteins found in the blood and tissue fluids that are actively involved in the body’s immune system, supporting the functioning of antibodies. The activation of C3 and C4 ensures a normal immune response of the body. The components regulate inflammation, activate phagocytes, and kill bacteria and viruses.
The levels of C3 and C4 are reduced due to a number of diseases (e.g. rheumatic diseases, lupus (SLE)), where complement components are depleted when the immune system is activated and their low levels indicate autoimmune disease. The levels are also lower than normal in case of some liver diseases or various inherited defects.
Increased levels of complements occur in the acute phase of inflammation, especially in bacterial infections and chronic inflammations.

Zinc is vital for growth, the functioning of the immune system, skin health, nail and hair growth, wound healing, insulin synthesis, formation of spermatozoids in men, development of taste receptors, and so on. Sufficient levels of zinc are needed for the normal production and functioning of the cells of the immune system.
Prolonged zinc deficiency may increase susceptibility to infections and the incidence of colds, poor wound healing, increased hair loss, white patches on nails, poor blood circulation (fainting), etc.
Low levels of zinc in the blood can be caused by low levels of zinc in food but also by intense physical activity, stress, gastrointestinal diseases, long-term use of iron supplements, etc. Excessive alcohol consumption can lead to an increased urinary excretion of zinc.
Elevated zinc values may occur in case of thyroid diseases, hypertension and kidney diseases.
Zinc is found in meat, fish, seafood, eggs, whole grain products, nuts, raisins, seeds, yeast, etc

Selenium is an antioxidant that helps the immune system to function. It also affects the production and reproduction of thyroid hormones (contained in spermatozoids).
The human body develops oxidative stress as a result of smoking, an excessive consumption of alcohol, exposure to chemicals and UV radiation as well as due to inflammation and chronic diseases. Such effects can lead to premature cell damage and aging. The immune system weakens and becomes increasingly susceptible to infections.
Selenium can be found in some key enzymes inhibiting oxidative stress. Long-term selenium deficiency negatively affects heart muscles and the thyroid gland, and it also causes bone breakdown and a loss of appetite.
Clinical symptoms of selenium overdose and poisoning include a garlic-like breath odour, brittle nails, hair loss, reddish and swollen skin on the limbs and blood clotting disorders among others.
Selenium is found in egg yolk, nuts, fish, seafood, meat, mushrooms, broccoli, whole grain products, garlic, onions, dairy products, cabbage and many other products.

IgA is the main immunoglobulin found in mucous secretions: tears, saliva, nasal secretions, respiratory, gastrointestinal and urogenital secretions, including breast milk.
The function of IgA is to protect mucous membranes against bacteria and viruses. Increased levels of IgA antibodies in the blood occur especially in respiratory and chronic gastrointestinal infections. Elevated results are also seen in case of liver and kidney diseases, autoimmune rheumatic diseases and alcohol abuse.
IgA levels in the blood are reduced in case of congenital IgA deficiency, which is relatively common (1:500-800). It is one of the mildest forms of immunodeficiency, and it often does not result in any complaints or illnesses. However, some people may be more prone than others to inflammation of the gastrointestinal tract and respiratory tract, as well as autoimmune and allergic diseases. For example, IgA deficiency is 10-15 times more common in patients with celiac disease.

IgG is the most abundant antibody found in the blood. The main function of antibodies is to help remove various infectious agents (bacteria, viruses, fungi and their toxins) from the body.
Normal levels of serum IgG are very important for immune protection. Elevated levels of IgG antibodies to some pathogens indicate a chronic disease or a past disease. In case of some infectious diseases, IgG antibodies completely disappear from the blood after recovery, while in others they persist for a long time or even for a lifetime.
Vaccination is also based on the development of IgG antibodies to the pathogen. Vaccination induces the production of specific IgG antibodies by an attenuated or killed infectious agent. Upon second exposure to the same pathogen, the antibodies are able to kill it.
The antibodies penetrate the placenta during pregnancy and provide protection against infection after birth and during the first months of baby´s life. By the end of the first year, the infant has an IgG level of approximately 70% of that of an adult.
IgG levels in the blood may be elevated in chronic inflammations, joint, liver, blood-borne, skin and autoimmune diseases, and gout.
Decreased IgG levels may occur due to protein deficiency (e.g., starvation) and as a result of renal, hepatic and intestinal diseases, severe burns and blood-borne diseases.
Very low levels of IgG in the blood occur in hereditary forms of immunodeficiency and their incidence is low.

IgM is the first antibody produced in response to an infectious agent entering the body. In a blood test, pathogen-specific IgM is detectable during the acute period of infection. However, it usually disappears quickly from the blood and does not provide sustained immune protection. Blood IgM levels are elevated in some liver and kidney diseases, fungal, mycoplasma, viral infections (e.g. EBV, HBV, HAV, CMV, etc.), in occurrence of parasites and acute inflammation.
Blood IgM levels are decreased in case of protein deficiency (starvation), protein loss due to renal, liver and gastrointestinal diseases, serious burns and blood-borne diseases. Very low levels of IgM in the blood occur rarely in patients with hereditary immunodeficiency.

Vitamin A is only obtained from food of animal sources in the form of retinol, and from food of plant origin as carotenoids (30-60% as beta-carotene). Vitamin A from animal sources is about 6 times more effective than plant-derived beta-carotene.
Vitamin A intake is hampered by drinking coffee and alcohol and in case of low acidity in the stomach.
Diabetes and hypothyroidism prevent the body from converting beta-carotene into vitamin A.
In case of sufficient vitamin A levels, about 50-80% of it is stored in the liver and, if necessary, is transported to the tissues. Some of vitamin A is stored in the adipose tissue, lungs, kidneys, retina and bone tissue.
Vitamin A ensures the normal development and good condition of respiratory, intestinal and urinary mucous membranes. Its deficiency increases the susceptibility to infections, as it promotes mucus secretion, which serves as an important barrier for bacteria.
Why is vitamin A necessary?
• it plays a crucial role in healthy vision
• helps to maintain the body’s resistance
• ensures the development of skin cells
• ensures the development and growth of cartilage, bones and teeth
• ensures the body’s fertility

Vitamin B12 is important for the synthesis of myelin surrounding nucleic acids, folate, amino acids, proteins and nerve fibres, the development of erythrocytes and immune system cells, and the normal functioning of haematopoiesis, the nervous system and skin. The active forms of vitamin B12 together with folate are involved in the metabolism of homocysteine in the body, resulting in a decrease in the level of homocysteine in the blood, which has a positive effect on cardiovascular function.
Vitamin B12 is only found in animal sources and its absorption is inhibited by excessive alcohol and coffee consumption, smoking, the use of oral contraceptives and laxatives, diseases affecting the gastric mucosa and other gastrointestinal diseases. B12 absorption decreases more frequently with age and due to vegetarian diet. Chronic B12 insufficiency results in anaemia, various neurological disorders, and a decrease in the body’s immune protection against infections, especially viral infections.

Why is Vitamin C necessary?
• boosts the body’s immune system
• contributes to the absorption of iron from plant sources
• for the function of the skin, gums, capillaries, teeth, ligaments and bones
• for normal wound healing
• participates in the restoration of the active form of vitamin E as an antioxidant
• etc.
White blood cells require vitamin C to cope with oxidative stress – the reactive particles that form during the destruction of foreign cells.
Vitamin C affects the immune system through its antioxidant effects. With long-term stress, infections and an unhealthy diet, the levels of vitamin C in the blood and white blood cells drastically decrease. Smokers have a higher need for vitamin C. Pregnant women and breastfeeding mothers also require larger quantities of vitamin C.
The need for vitamin C increases with alcoholism, frequent courses of antibiotics, inflammation of the intestinal mucosa, use of medication (e.g. analgesics, some anti-inflammatory and anti-allergic medicines, oestrogen-containing medicines) and intensive physical activity.
Vitamin C is obtained mostly from fruits, vegetables and berries.

D-vitamins are fat-soluble steroid hormones. The three sources of vitamin D are through sun exposure, food and supplements. Most of the necessary vitamin D is obtained by sun exposure.
Ultraviolet B (UVB) radiation in summer around midday on the hands and face for 10-15 minutes results in the synthesis of 800-1000 units of previtamin D3 in the skin, which is enough to cover the daily needs of an adult person. The vitamin is mainly stored in the adipose tissue for about 2 months. Overweight people often suffer from chronic vitamin D deficiency due to the vitamin not reaching their bloodstream.
Vitamin D is vital for the immune system to function properly. Vitamin D receptors have been found in a number of cells of the immune system and, in the case of adequate levels, they are able to activate and kill invading pathogens. Vitamin D has an anti-infective and anti-inflammatory effect. It regulates bone metabolism: low levels of vitamin D increase the risk of osteoporosis.
Vitamin D also affects blood clotting, blood pressure, nervous tissue function and has a beneficial effect on blood sugar metabolism. There is an association between vitamin D deficiency (< 50 nmol/l) and the incidence of cancer, multiple sclerosis, various infections, hypertension, diabetes, asthma, cardiovascular diseases, rheumatoid arthritis and other autoimmune diseases.