Final answer:
Lithium is a common long-term treatment for bipolar disorder that helps stabilize mood. Blood samples are collected and centrifuged to measure lithium levels in the plasma.
Step-by-step explanation:
A bipolar patient with two hospitalizations for mania is taking lithium. Lithium is commonly used as a long-term treatment for bipolar disorder as it helps stabilize mood and reduce the frequency and severity of manic and depressive episodes.
It is important to monitor the lithium levels in the blood to ensure they are within the therapeutic range. Blood samples are collected and centrifuged to obtain plasma, from which the lithium levels can be measured.