Markham Nightengale, MD

Markham L. Nightengale, MD

Markham Nightengale, MD always knew medicine was his calling. He comes from a long line of doctors who helped shape his curiosity for science into a career as a physician. When it came time to choose a specialty, gastroenterology was the obvious choice. Dr. Nightengale says, “GI is a challenging field and I am someone who likes a challenge.” He also appreciates the opportunity to offer ongoing care to each patient, working with them from diagnosis throughout treatment, unlike some areas of medicine, where doctors may only see the patient once or twice during the course of care.

Dr. Nightengale graduated with honors from Oklahoma State University, completing an undergraduate degree in Biochemistry. He attended medical school at the University of Oklahoma Health Science Center. He completed his internship and residency in Internal Medicine at the Mayo Graduate School of Medicine in Rochester, Minnesota, then did his fellowship in Gastroenterology at Baylor University Medical Center in Dallas.

As a 25-year veteran in gastroenterology, Dr. Nightengale has observed a number of scientific advancements that have significantly impacted patient care and the GI field as a whole, most notably are endoscopic ultrasound machines, which allow gastroenterologists to quickly diagnose problems and effective treatments for hepatitis C. In fact, today’s hep C treatments are cured in 92 percent of the cases. Previous treatment methods for hepatitis C had only a 45 percent success rate and were often painful for the patients.

Though Dr. Nightengale’s expertise incorporates a broad number of GI conditions and treatments, he is specially trained as a hepatologist and intensely interested in the diagnosis and treatment of liver disease.

As a physician with Adult Gastroenterology Associates, Dr. Nightengale appreciates the enthusiasm of his fellow physicians and the medical staff. He says, “You could not choose a better team for your care—everyone genuinely enjoys caring for patients and delivering a great healthcare experience.”

When he’s not treating patients, Dr. Nightengale enjoys reading and spending time with his wife and three adult children. He also likes hiking in places such as Yosemite, the Appalachian Trail, the Adirondacks, the Pacific Crest Trail, and the John Muir Trail in the Sierra Nevadas.

Just call me… keep me informed. If you have a problem, call. If I don’t know about your problem, I can’t make it better!– Markham Nightengale, MD Adult Gastroenterology Associates, Tulsa, OK

Education, Memberships, Awards, and Affiliations

  • Bachelor of Science in Biochemistry: Oklahoma State University – Stillwater, OK
  • Doctor of Medicine: University of Oklahoma Health Science Center – Oklahoma City, OK
  • Internship and Residency in Internal Medicine: Mayo Graduate School of Medicine – Rochester, MN
  • Fellowship in Gastroenterology: Baylor University Medical Center – Dallas, TX
  • Distinguished Service Award while at Oklahoma State University
  • Phi Kappa Honor Society (top 10% of his class) at Oklahoma State University
  • Alpha Omega Alpha award from the University of Oklahoma Health Science Center
  • American Gastroenterological Association
  • American College of Physicians
  • American Medical Association
  • Oklahoma State Medical Society
  • Arkansas-Oklahoma Endoscopic Society
  • Tulsa County Medical Society


  • Gastroenterology
  • Internal Medicine



Practicing medicine since 1993




Adult Gastroenterology Associates


Tulsa Endoscopy Center

4200 Skelley Dr., Suite 100
Tulsa, Oklahoma 74135

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