JLP Phlebotomy Practice Exam

Therapeutic Drug Monitoring centers on obtaining a blood concentration of a drug at a specific time after dosing to guide dose adjustments and keep levels within a safe, effective range. The step where a phlebotomist asks about when the patient last took the medication is essential because the interpretation of the drug level depends on timing relative to the last dose. Drug levels rise after administration and fall as the body eliminates the drug, so knowing the exact timing helps determine whether the measured concentration reflects a trough, peak, or an in-between level and whether dose adjustments are needed. The other listed tasks—checking liver enzymes, measuring glucose, and assessing electrolyte balance—are important lab tests in their own right but are not part of the drug level monitoring process.