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Serum Blood Level


Updated June 18, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Serum blood level describes the amount of a given medication present in your blood at the time of testing. Blood serum is the liquid part of the blood that contains no clotting factors or blood cells.

Some medications used to treat bipolar disorder require serum blood level testing. People taking lithium in particular must be tested regularly, as there is a narrow "therapeutic window" for lithium. That means that the difference between a therapeutic level and toxic level can be small in some individuals.

Other medications that require serum blood level testing include Tegretol (carbamazepine) and Depakote / Depakene (sodium valproate, valproic acid).

Pronunciation: Serum: SEER-uhm
Plurals: Serums (as above), Sera: SEER-uh
Common Misspellings: Seerum, seram, serim and similar combinations.
When Georgia had her serum blood level of Lithium tested, the results showed that her level was too high, and her doctor adjusted her daily dosage of Lithium downward.

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