Hematology deals with diseases of the hematopoietic and lymphatic organs, and one branch of it deals with disorders of blood clotting.
Fortunately, severe hematopoietic diseases are rare, but abnormalities in blood counts are very common during routine blood sampling. Complicating matters is the fact that in Hungary, blood tests mean one thing in an everyday sense and something different in a medical sense. According to the vernacular, ‘complete blood count’ is the collective term for all tests performed on blood samples. However, doctors only mean a certain test: an examination of the blood's components, such as white blood cells, red blood cells, a platelet (thrombocyte) count and a few other parameters that are mainly indicative of the condition of the blood (for example hemoglobin, the hematocrit level, or the distribution of white blood cells). Quantitative changes in any of these can disturb the functioning of the body, whether the amount is higher or lower than necessary. It is also possible for several different cellular elements to increase or decrease simultaneously.