Which color tube is required for collecting a sample for Lithium monitoring?

The correct choice for collecting a sample for Lithium monitoring is the red tube. This tube is typically used for serum collection, which is necessary for measuring the levels of lithium in the bloodstream. Lithium is a medication commonly used to treat bipolar disorder, and monitoring its levels is crucial to ensure therapeutic effectiveness while avoiding toxicity.

The red tube allows for the separation of serum after coagulation has occurred, enabling accurate measurement of the drug levels. It's important to understand that the other color tubes serve different purposes: the green tube is often used for plasma testing, the yellow tube for blood cultures or tissue typing, and the SST (Serum Separator Tube) functions similarly to red tubes by allowing serum separation but contains a gel that helps with this process.