Blood is the only fluid tissue of the human body that circulates in the placenta blood vessels. The most important task of blood is the distribution of oxygen throughout the body and transporting carbon dioxide to the lungs. Blood transfers nutrients, electrolytes and metabolism waste. Blood also transfers a number of regulatory substances, including hormones, enzymes and vitamins. Blood has a clotting ability, and due to the presence of immune cells it is involved in building the body’s immune system, and thanks to the content of the buffer compounds, it maintains essential homeostasis.
Blood is not a random mixture of cellular components, and various chemical compounds. It has a specific composition of both quantitative and qualitative components. That means, any substance in the blood, any chemical electrolyte or specific cell has a strictly defined amount a specifies physiological norm. Blood carries substances which correspond to the the work of all glands and organs of the body. Any deviation from standard may result in blood disorders or disease. Laboratory blood tests can often complement clinical research, but due to its specific nature, is used as a primary diagnostic test (eg, deficiency of hemoglobin and/or red blood cells indicates anemia ).
Laboratory blood tests can be divided into morphological and biochemical ones.
A morphological examination is a basic blood test, which defines a quantitative and qualitative amount of morphological components.
Primary morphology includes:
- number of erythrocytes;
- blood platelets and leukocytes and their fractions.
Biomechanics which determine the concentration of chemicals in blood plasma mainly refer to:
- hormones (e.g.thyroid – T3 , T4, TSH);
- enzymes (ALT, AST, CK, LDH);
- blood proteins (albumin, immunoglobulins, fibrinogen);
- electrolytes (Na, K , Fe, Mg, Ca, etc.);other substances (e.g., glucose, cholesterol, triglycerides).