Chapter 30
Clinical Laboratory Tests
Reading the numbers that guide therapy
Clinical Laboratory Tests: General Principles
Laboratory tests are performed to discover a disease, confirm or differentiate a diagnosis, stage or classify a disease, and monitor therapy. Pharmacists monitor labs to assess drug effects, determine dose, assess the need for alternate therapy, and prevent test misinterpretation from drug interference.
Labs are the pharmacist's window into a patient's physiology. Tests should be ordered only if the result will affect management. This chapter is about knowing normal ranges, what abnormal values mean, and the formulas (RBC indices, ANC, creatinine clearance) that turn raw numbers into decisions.
Screening vs Diagnostic
Screening tests are used in patients with NO signs/symptoms (e.g., serum cholesterol for CV risk). Diagnostic tests are used when signs/symptoms exist or a screen is abnormal. Do not chase normal values in a stable patient -- resist the urge to 'do something.'
📖 “Labs: discover/confirm/differentiate/stage disease, monitor therapy. Pharmacists monitor to assess drug effect, determine dose, assess alternate therapy, prevent interference. Order only if result affects management. Screening (no symptoms) vs diagnostic (symptoms).”