Plasma level
The plasma level (also called plasma concentration or inaccurately also called blood level) describes the measurable concentration in the blood plasma of an endogenous substance (e.g. blood sugar ) or a foreign substance (e.g. a drug or another foreign substance absorbed into the blood ). Similarly, the term serum level describes the corresponding substance content in the blood serum . In the case of pharmacologically active substances, one speaks of an effective level , which ideally should be within the therapeutic range . The plasma half-life is also an important parameter .
Since the concentration of important physiological substances is kept in a certain “normal range” by regulation mechanisms , deviations have a diagnostic value.