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Gwendolyn A. McMillin, Ph.D.

last modified 2013-08-09 10:43 — by Kimberley Crist

Associate Professor (Clinical), University of Utah Pathology

Gwendolyn A. McMillin, Ph.D.

Contact Info

Email Address: gwen.mcmillin {at}

Office Phone Number: 801-583-2787 ext. 2671

Location: ARUP Laboratories

Division: Clinical Pathology

Supporting Staff:   Mishka Foster  



  • Medical Director, Associated Regional and University Pathologists (ARUP) Laboratories, Clinical Drug Abuse Testing, Salt Lake City, Utah.
  • Medical Director, Associated Regional and University Pathologists (ARUP) Laboratories, Trace Elements, Salt Lake City, Utah.
  • Co-Medical Director, Associated Regional and University Pathologists (ARUP) Laboratories, Pharmacogenomics, Salt Lake City, Utah.

About Gwendolyn A. McMillin, Ph.D.

Dr. McMillin is interested in laboratory testing that supports and improves drug therapy.  As such, she serves as the Medical Director at ARUP Laboratories over testing for therapeutic drugs, drugs of abuse, metals, and is Co-Medical Director  over pharmacogenetics. She actively pursues research in these areas to better understand clinical utility of existing testing and to develop and validate new testing.  Areas of recent focus include:

1.  Pre-therapeutic pharmacogenetic testing to select warfarin dosing.  Several analytical methods for warfarin genotyping have been evaluated in our pharmacogenetics laboratory, and a clinical study is underway in collaboration with the University of Utah Anticoagulation Services Group and the Orthopaedic Center.  This study compares outcomes when warfarin dose is selected using genetic information as compared to outcomes when warfarin dose is selected using conventional means.  Pharmacogenetic testing related to tamoxifen, irinotecan, and various neuroleptics have also been studied in our laboratory.

2.  Application of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for quantitative testing of drugs in urine, blood, serum/plasma, and meconium has generated rapid multi-analyte tests with unheralded sensitivity and specificity.   This technology is being applied in our drug testing laboratory to both drugs of abuse (e.g. opiates, benzodiazepines, nicotine) and therapeutic drugs (e.g. antipsychotics, anticonvulsants, antidepressants).  The new assays, when compared to existing assays, exhibit dramatic improvements in efficiency, accuracy, sensitivity, specificity, and precision.

3.  Metals are much like drugs, exhibiting variable absorption, metabolism, protein binding, and elimination.  As such, laboratory tests designed to detect and quantify metals should consider the related pharmacokinetics or toxicokinetics.  Recent projects conducted in our metals laboratory have focused on separating clinically or toxicologically significant fractions of metals for quantification.  For example, we developed an arsenic fractionation method which separates and quantifies the various species of arsenic. This fractionation is important due to the differential toxic potential of inorganic arsenic, methylated metabolites of arsenic, and the relatively non-toxic but commonly observed organic forms of arsenic.  We also developed a novel method for measuring the free fraction of copper, important to the diagnosis and monitoring of Wilson Disease.

Selected Publications

  • 1. Coles R, Kushnir M, Nelson G, McMillin GA, Urry FM. (2007) Simultaneous determination of codeine, morphine, hydrocodone, hydromorphone, oxycodone and 6-acetylmorphine in urine, serum, plasma, whole blood and meconium by LC-MS/MS. Journal of Analytical Toxicology, Jan/Feb;31(1):1-10.
  • 2. Yang X, Janatova J, Juenke JM, McMillin GA, and Andrade JD. (2007) An ImmunoChip for simultaneous detection of antiepileptic drugs using an enhanced one-step homogeneous immunoassay. Analytical Biochemistry, 365:222-9.
  • 3. Marin SJ, Coles R, Urry FM, and McMillin GA. (2007) Confirmation Test for cannabinoids in meconium using two dimensional gas chromatography with mass spectrometry detection. Journal of Chromatography B, 858:60-4.
  • 4. Marin SJ, Coles R, Merrell M, McMillin GA. (2008) Quantitation of Benzodiazepines in Urine, Serum, Plasma and Meconium by LC-MS/MS, Journal of Analytical Toxicology, 32:491-8.
  • 5. McMillin GA, Travis JJ, Hunt JW. (2009) Direct measurement of free copper in serum or plasma ultrafiltrate, American Journal of Clinical Pathology, 131(2):160-5.
  • 6. Marin SJ, Moore C, McMillin GA. (2009) Cross-reactivity of phentermine with and immunoassay designed to detect amphetamine in a meconium specimen, Clinical Chemistry, 55(3): 589-90.
  • 7. Marin SJ, Keith L, Merrell M, McMillin GA (2009). Comparison of drugs of abuse detection in meconium by EMIT®II and ELISA, Journal of Analytical Toxicology, 33(3):148-54.
  • 8. Marin SJ, Keith L, Merrell M, McMillin GA (2009). Evaluation of a new ELISA kit for the detection of benzodiazepines in meconium, Journal of Analytical Toxicology, 33(3):177-81.
  • 9. Courtney JB, Harney R, Li Y, Lundell G, Juenke J, McMillin GA, Salamone S (2009). Determination of busulfan in human plasma using an ELISA format, Therapeutic Drug Monitoring, 31(4):489-94.
  • 10. De BK, Jiminez E, De S, Sawyer J, McMillin GA (2009). Analytical performance characteristics of the Abbott Architect i2000 tacrolimus assay: comparisons with liquid chromatography tandem mass spectrometry (LC-MS/MS), Clinica Chemica Acta, 410(1-2):25-30.
  • 11. MacKay M, Winther B, Rusho B, McMillin GA, Jackson D (2009). The physical and chemical stability of iron sucrose in parenteral nutrition. Nutrition in Clinical Practice, 24:733-7.
  • 12. Beumer JH, Boisdron-Celle M, Clarke W, Courtney JB, Egorin MJ, Gamelin E, Harney RL, Hammett-Stabler C, Lepp S, Li Y, Lundell GD, McMillin G, Milano G, Salamone SJ (2009). Multicenter evaluation of a novel nanoparticle immunoassay for 5-fluorouracil on the Olympus AU400 analyzer, Therapeutic Drug Monitoring, 31(6):688-94.
  • 13. Lenzini P, Wadelius M, Kimmel S, Anderson JL, Jorgensen AL, Pirmohamed M, Caldwell MD, Limdi N, Burmester JK, Dowd MB, Angchaisuksiri P, Bass AR, Chen J, Eriksson N, Rane A, Lindh JD, Carlquist JF, Horne BD, Grice G, Milligan PE , Eby C, Shin J, Kim H, Kurnik D, Stein CM, McMillin G, Pendleton RC, Berg RL, Deloukas P, Gage BF (2010). Integration of genetic, clinical, and INR data to refine warfarin dosing. Clinical Pharmacology & Therapeutics. 87(5):572-8.
  • 14. McMillin GA, Melis R, Lyon E, Wilson A, Vinik R, Wanner N, Strong M, and Pendleton RC (2010). Accuracy of gene-based warfarin dosing applied prospectively to an orthopedic surgery population. Therapeutic Drug Monitoring, 32(3):338-45.
  • 15. McMillin GA, Juenke JM, Tso G, Dasgupta A (2010). Estimation of carbamazepine and carbamazepine 10, 11–epoxide concentrations in plasma using mathematical equations generated with two carbamazepine immunoassays American Journal of Clinical Pathology, 133:728-36.
  • 16. Johnson-Davis KL, McMillin GA, Juenke JM, Ford CD, and Petersen FB (2010). Which dose is best? Report of an obese patient with poorly predicted pharmacokinetics for intravenous busulfan, when based on first dose sampling. Clinical Chemistry, 56(7):1061-4.
  • 17. Breaud AR, Harlan R, Dibussolo J, McMillin GA, Clarke W (2010). A rapid and fully-automated method for the quantitation of tricyclic antidepressants in serum using turbulent flow liquid chromatography-tandem mass spectrometry. Clinica Chimica Acta, 411(11-12):825-32.
  • 18. Johnson-Davis KL, Thompson C, Clark C, McMillin GA, Lehman C (2010). High amphetamine/methamphetamine concentrations in urine can cause error codes on the Ortho Vitros® Fusion 5,1 automated chemistry analyzer. Journal of Analytical Toxicology, 34(9):607-8.
  • 19. Marin SJ, Merrell M, McMillin GA. Drugs of Abuse Detection in Meconium; a Comparison Between ELISA and Biochip Microarray. Journal of Analytical Toxicology, In press.
  • 20. Greene DN, Lehman C, McMillin GA. Evaluation of the Integrated E-Z Split Key® Cup II for rapid detection of 12 drug classes in urine. Journal of Analytical Toxicology, In press.
  • 21. Marin SJ, Christensen RD, Baer VL, Clark CJ, McMillin GA. Nicotine and metabolites in paired meconium and umbilical cord specimens. Therapeutic Drug Monitoring, In press.
  • 1. Lyon E, McMillin G and Melis R. (2008) Pharmacogenetic testing for warfarin sensitivity. Clinics in Laboratory Medicine, 28(4):525-537.
  • 1. McMillin GA. (2007) Pharmacogenetics. In: Tietz Fundamentals of Molecular Diagnostics, 6th Ed, edited by C Burtis, E Ashwood, and D Bruns. Saunders Elsevier (St Louis, MO), pp.197-215.
  • 2. Burtis C, Bruns D, Roberts W, McMillin GA. (2008) Reference Information for the Clinical Laboratory and Therapeutic Drugs. In: Tietz Fundamentals of Clinical Chemistry, 6th Ed, edited by C Burtis, E Ashwood, and D Bruns. Saunders Elsevier (St Louis, MO), pp.836-73.
  • 3. Moyer T, McMillin GA, and Shaw L. Therapeutic Drugs. (2008) In: Tietz Fundamentals of Clinical Chemistry, 6th Ed, edited by C Burtis, E Ashwood, and D Bruns. Elsevier Saunders (St Louis, MO), pp.539-61.
  • 4. McMillin GA and Bornhorst JA. (2008) Toxic Element Testing with Clinical Specimens. In: Handbook of Drug Monitoring Methods, edited by A Dasgupta. Humana Press (Totowa, NJ), pp. 263-82.
  • 5. Stone J, McMillin G, Erickson C, and Kwong TC. (2008) Analytical and Clinical Toxicology. In: Self Assessment in Clinical Laboratory Science II, edited by AHB Wu. AACC Press (Washington, DC), pp.265-93.
  • 6. McMillin G, Melis R, and Bornhorst J. (2009) Alcohol Abuse and Dependency: Genetics of Susceptibility, and Pharmacogenetics of Therapy. In: Critical Issues in Alcohol and Drugs of Abuse Testing, AACC Press (Washington, DC), pp.13-27.
  • 7. Johnson-Davis K and McMillin GA. (2010) Enzymes. In: Clinical Chemistry: Principles, Procedures, Correlations, 6th Ed, edited by ML Bishop, EP Fody, LE Schoeff. Lippincott, Williams & Wilkins (Baltimore, MD), pp.281-308.
  • 8. Juenke J and McMillin G. (2010) Analytical Support of Anticonvulsant Drug Monitoring; beyond the immunoassay. In: Advances in Chromatographic Techniques for Therapeutic Drug Monitoring, CRC Press (Boca Raton, FL), pp.85-101.
  • 9. Marin S and McMillin G. (2010) LC-MS/MS Analysis of 13 Benzodiazepines and Metabolites in Urine, Serum, Plasma and Meconium. In: Methods in Molecular Biology: Clinical Applications of Mass Spectrometry, Humana Press (Totowa, NJ), pp. 89-105.
  • All Publications: Click Here

Honors and Awards

  • 1993 Association for Women in Science Award
  • 1993 Pre-doctoral Fellowship Award ($6,000), American Foundation for Pharmaceutical Education
  • 2003 Paul E. Strandjord Young Investigator Award, Academy of Clinical Laboratory Physicians and Scientists
  • 2004 Paul E. Strandjord Young Investigator Award, Academy of Clinical Laboratory Physicians and Scientists
  • 2004 Young Investigator Award, TDM and Toxicology Division of the American Association for Clinical Chemistry
  • 2009 Outstanding Speaker Award, American Association for Clinical Chemistry

Professional Education

  • 1985-1989 B.A. Grinnell College (Psychology) Grinnell, IA
  • 1990-1994 Ph.D. University of Utah (Pharmacology) Salt Lake City, Utah
  • 2001-2004 Post-doctoral Fellowship University of Utah (Clinical) Chemistry Salt Lake City, Utah