CAP Pro Course - Chemistry - Therapeutic Drug Monitoring (2026 & 2027)

Author: Kevin F. Foley PhD, DABCC, MLS, SC
Reviewers: DeRhonda Crawford, MLS(ASCP) and Joshua J. Cannon, MS, MLS(ASCP)CMSHCM

Continuing Education Credits

Objectives

  • Define therapeutic drug monitoring (TDM) and compare and contrast it with drugs of abuse testing.
  • Identify categories of therapeutic drugs that are frequently monitored in clinical settings.
  • Describe the different stages of drug disposition over time and list factors that can influence drug distribution.
  • Describe what is meant by a drug's half-life and how this relates to peak and trough concentrations in the serum.
  • Discuss criteria for reporting TDM results, including documentation of drug administration information, when appropriate, and critical result reporting.

Course Outline

  • Define therapeutic drug monitoring and compare and contrast it with drugs of abuse testing.
      • What is Therapeutic Drug Monitoring?
      • How is Therapeutic Drug Monitoring Used?
      • What is the goal of therapeutic drug monitoring (TDM)?
      • A laboratorian is asked to provide the therapeutic range for a drug for which the laboratory offers therapeutic drug monitoring. What value is being r...
      • What is the term given to the range of test values between the minimum effective concentration and the toxic concentration of a drug?
      • A child arrives at the laboratory's outpatient draw station for a blood test. The child regularly comes for a phenobarbital test, but the physician ha...
  • Identify categories of therapeutic drugs that are frequently monitored in clinical settings.
      • Types of Drugs That Are Monitored
      • Drugs Measured with Therapeutic Drug Monitoring (TDM)
      • Categories of Therapeutic Drugs Commonly Monitored by TDM
      • Some Common Therapeutic Drugs monitored by TDM
      • Miscellaneous Therapeutic Drugs
      • Which of the following drugs is not routinely measured using therapeutic drug monitoring (TDM) techniques to adjust the therapeutic dose?
      • There are assays that are used more to assess overdose and toxicity than to adjust the therapeutic dose. Which of the following drugs has therapeutic ...
      • A laboratorian is asked to find and validate a therapeutic drug monitoring (TDM) assay for morphine. The rationale is that opiate overdoses are common...
  • Describe the different stages of drug disposition over time and list factors that can influence drug distribution.
      • Absorption, Distribution, Metabolism, and Excretion (ADME)
      • Absorption, Distribution, Metabolism, and Excretion (ADME), continued
      • Routes of Administration
      • Establishing and Maintaining a Therapeutic Range
      • Other Factors That Affect Drug Disposition
      • Which of the following laboratory tests would not be ordered to compliment or shed light on the TDM result?
      • A plasma specimen is received in the laboratory for peak gentamicin measurement. The physician dosing the patient notes that the patient has end-stage...
      • A patient who has been taking phenytoin therapeutically for an extended period develops a condition that decreases serum protein. Phenytoin is highly ...
      • A serum/plasma specimen is received in the laboratory for therapeutic drug monitoring (TDM). The patient has been taking this same medication at the s...
  • Describe what is meant by a drug's half-life and how this relates to peak and trough concentrations in the serum.
      • Acceptable Sample Types
      • Sample Collection Times
      • Laboratory Methods for Therapeutic Drug Monitoring (TDM)
      • Which of the following specimens is not acceptable for therapeutic drug testing?
      • A nurse from a physician's office delivers a plasma sample for lithium measurement. The sample was delivered in an aliquot tube; the original collecti...
      • A serum sample for digoxin measurement arrives in a serum separator tube at the laboratory. What effect could the gel barrier have on the test result?
      • Which of the following refers to a trough sample?
      • Which route of administration would most quickly lead to measurable drug levels in the serum?
      • Which of the following factors is not likely to affect a drug's absorption?
      • Which of these therapeutic drugs is tested using the analytic methodology of ion-selective electrode (ISE)?
  • Discuss criteria for reporting TDM results, including documentation of drug administration information, when appropriate, and critical result reporting.
      • Clinical Interpretation of TDM Results
      • Critical Values
      • Will Pharmacogenomics Replace Therapeutic Drug Monitoring (TDM)?
      • A sample is received from the cardiac unit of your facility for a stat digoxin level. Your instrument reports the result as 3.0 ng/mL and flags it as ...
      • A patient arrives at the outpatient laboratory with an order for a digoxin test. The order states that the blood sample is to be collected eight hours...
      • People respond to drugs differently due to individual differences in enzymes that metabolize the drugs. Which of the following statements is true rega...
      • A critical high phenobarbital level is reported by your laboratory. What must be done when communicating this result to the patient's provider?
      • A sample for therapeutic drug monitoring (TDM) arrives in the laboratory from an outreach clinic. The sample is in a gel-barrier tube. The sample was ...
  • References
      • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: This program is designed as an educational and training tool for medical laboratory scientist and medical laboratory technician personnel, medical laboratory science students and interns, pathology residents, and practicing pathologists.
Author Information: Kevin F. Foley, PhD, DABCC, MLS, SC is the director of clinical pathology for the Kaiser Permanente Northwest region. He also teaches clinical chemistry at Oregon Health Sciences University. Dr. Foley earned his PhD in clinical pharmacology and toxicology at East Carolina School of Medicine in North Carolina. He recieved a PhD in clinical pharmacology and toxicology from Brody School of Medicine, Greenville, NC. He has been working in laboratory medicine for over 15 years, starting his career as a medical technologist.
The author has no conflict of interest to disclose.
Reviewer Information:
DeRhonda Crawford, MLS(ASCP) is the chemistry supervisor at Gwinnett Medical Center in Lawrenceville, Georgia and the technical supervisor for the Gwinnett Medical Center in Duluth, Georgia. She holds a BS in Medical Technology from the Medical College of Georgia.
Joshua J. Cannon, MS, MLS(ASCP)CMSHCM received his Bachelor of Science and Master of Science in Medical Laboratory Science from Thomas Jefferson University in Philadelphia, PA. He holds Medical Laboratory Scientist and Specialist in Hematology certifications through the ASCP Board of Certification. He was a professor at Thomas Jefferson University for seven years before transitioning into his current role as Education Developer at MediaLab by Vastian. His areas of expertise and professional passions include clinical hematology and interprofessional education. 

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