With the aim of determination of biochemical indicators variability in the plasma and milk and hematological indicators regarding the daily lactose content classes (indicating the mastitis risk) and somatic cell counts classes (indicating the animal’s health status), blood and milk of 75 Holstein cows were sampled. The cows were reared on a commercial dairy farm. A statistical analysis demonstrated that the lactation stage, parity, and statistically significant monthly measurement P < 0.01) affected both the biochemical and hematological parameters. The differences between the analyzed biochemical and hematological parameters due to the mastitis score classes (according to the daily lactose content, DLC, and the somatic cell count, SCC) were present and statistically significant (P < 0.05) in some traits. Furthermore, different trends regarding the mastitis scoring (DCL of SCC) were determined in some traits. Therefore, when using the test-day records as an animal’s mastitis risk and health status indicator, both scoring ways should be used. Finally, in the case of a mastitis risk or mastitis occurrence, other diagnostic methods (such as various mastitis tests) should be used for the sake of an unambiguous detection.