Dennis J. Dietzen, PhD

Dennis J. Dietzen, PhD

Professor, Pathology & Immunology
Section Head, Pediatrics Lab


  • Laboratory & Genomic Medicine

Additional Titles

  • Professor, Pediatrics
  • Medical Director, Laboratory Services, St. Louis Children’s Hospital
  • Medical Director, Laboratory Services, Children’s Specialty Care Center


  • BS: Chemistry: Marian University, Indianapolis, IN (1986)
  • PhD: Biochemistry and Molecular Biology: Indiana University (1992)
  • Postdoctoral Research Fellowship: Washington University (1995)
  • Postdoctoral Fellowship, Clinical Chemistry: Washington University (1995)

Board Certifications

  • Diplomate, American Board of Clinical Chemistry, 1997


  • President, American Association for Clinical Chemistry, 2018
  • Miriam Reiner Award, AACC Capital Section, 2018
  • Roger L. Boeckx Lectureship, Children’s National Medical Center, 2013
  • Outstanding Contributions to Pediatric Clinical Chemistry, AACC, 2012

Clinical Interests

  • Pediatric Clinical Laboratory Medicine
  • Inborn Errors of Metabolism
  • Clinical Toxicology
  • Clinical Applications of Mass Spectrometry

Research Interests

My research activities focus on improving existing analytic diagnostic tools and expanding the repertoire of informative biomolecules available for disease detection in children. We have developed novel analytic tools for the detection of inborn errors of metabolism and drug exposure in children and continue to explore the value of broad metabolic profiling in conditions such as pre-eclampsia, intrauterine growth retardation, liver failure, and neonatal hypoglycemia.

Selected Publications

Dietzen DJ, Weindel AL, Carayannopoulos MO, Landt M, Normansell ET, Reimschisel TE, Smith CH. Rapid comprehensive amino acid analysis by liquid chromatography/tandem mass spectrometry: comparison to cation exchange with post-column ninhydrin detection. Rapid Commun Mass Spectrom. 2008;22(22):3481-8. doi:10.1002/rcm.3754 PMID:18853396
Dietzen DJ, Rinaldo P, Whitley RJ, Rhead WJ, Hannon WH, Garg UC, Lo SF, Bennett MJ. National academy of clinical biochemistry laboratory medicine practice guidelines: follow-up testing for metabolic disease identified by expanded newborn screening using tandem mass spectrometry; executive summary. Clin Chem. 2009;55(9):1615-26. doi:10.1373/clinchem.2009.131300 PMID:19574465
DeMarco ML, Dietzen DJ, Brown SM. Sweating the small stuff: adequacy and accuracy in sweat chloride determination. Clin Biochem. 2015;48(6):443-7. PMID:25530017
Dietzen DJ, Bennett MJ, Lo SF, Grey VL, Jones PM. Dried Blood Spot Reference Intervals for Steroids and Amino Acids in a Neonatal Cohort of the National Children’s Study. Clin Chem. 2016. PMID:27784706
Dietzen DJ. Fifty Shades of Yellow. Clin Chem. 2017;63(5):937-938. PMID:28320762
Wiencek JR, Dietzen DJ, Murray T, Dawling S, Colby JM, Nichols JH. Persistently increased alloisoleucine in a patient with seizures. Clin Chem 2018;64:1433-1437. PMID:30266717
Farnsworth CW, Dietzen DJ, Roper SM. Atypical findings on a urine organic acid profile. J Appl Lab Med. 2020;5:388-393.
Tesfazghi MT, Bardelmeier R, Saunders AN, Riley SM, Roper SM, Dietzen DJ. Development and implementation of one-step, broad-spectrum, high-sensitivity, drug screening by tandem mass spectrometry in a pediatric population. J Appl Lab Med 2022;7:409-420.
Lyle AN, Pokuah F, Dietzen DJ, Wong ECC, Pyle-Eilola AL, Fuqua JS, Woodworth A, Jones PM, Akinbami LJ, Garibaldi L, Vesper HW. Current state of pediatric reference intervals: a call to correctly describe the biochemistry of child development. JAMA Pediatr 2022;176:699-714.
Marzinke MA, Clarke W, Dietzen DJ, Hoofnagle AN, McMillin GA, Willrich MAV. The VALIDity of laboratory developed tests: leave it to the experts? J Mass Spectrom Adv Clin Lab 2023;

Susan Keen