Norman Endoscopy Center
Norman's Newest and Most Advanced Dedicated Endoscopy Center
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NGA Providers

Charles Lackey, M.D., Robert Holbrook, M.D., and Joshua D. Whorton, M.D. specialize in the treatment of diseases of the digestive system. Our physicians have been serving the Norman community and residents of Oklahoma for over 25 years. Our physicians perform the latest diagnostic testing in gastroenterology at Norman Endoscopy Center, Norman’s newest and most advanced dedicated endoscopy center.

Our endoscopy center is located in the same building with our medical practice which makes it very convenient for our patients.  Our physicians treat such conditions as gastroesophageal reflux disease (GERD), Barrett’s esophagus, peptic ulcer disease, Crohn’s disease, ulcerative colitis, irritable bowel syndrome, colon cancer and hepatitis.  We are dedicated to providing every patient with the medical care they deserve.

Thank you for choosing the physicians of Norman Gastroenterology Associates.

Charles L. Lackey, M.D.

Charles L. Lackey, MD

Gastroenterologist
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Dr. Lackey is board certified in both Internal Medicine and Gastroenterology. He has been in private practice in Norman since 1983. Dr. Lackey is an active member of the medical staff at Norman Regional Health Systems and Norman Endoscopy Center.
Robert M. Holbrook, M.D.

Robert M. Holbrook, MD

Gastroenterologist
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Robert M. Holbrook, M.D., is board certified in both Internal Medicine and Gastroenterology. Raised in Norman, it was always his dream to practice medicine in his hometown. Dr. Holbrook joined Dr. Lackey in July of 2006 upon completion of his Gastroenterology training. He is an active member of the medical staff at Norman Regional Health Systems, Moore Medical Center, and Norman Endoscopy Center.
Joshua D. Whorton, M.D.

Joshua D. Whorton, MD

Gastroenterologist
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Dr. Joshua D. Whorton is board certified in both Internal Medicine and Gastroenterology. A native of Hollis, OK, the decision to stay in-state for his medical training and practice was an easy one. Dr. Whorton graduated Magna cum Laude from Oklahoma Baptist University in 2000. He graduated from OU College of Medicine in 2004. He completed residency in 2007 at OU Health Sciences Center where he was selected to serve as Chief Resident of Internal Medicine. Dr. Whorton also completed his three-year gastroenterology fellowship at the OU Health Sciences Center in 2011, with the last year serving as Chief Fellow.

Amber Crosby, APRN-CNP

Gastroenterologist
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Amber Crosby is a board certified Family Nurse Practitioner. She completed her BSN at Oklahoma City University in 2009 and her Master of Science at the University of Oklahoma in 2012. Since this time she has worked in Gastroenterology. Amber is an active member of the Crohn's and Colitis Foundation and served on the CCF National Scientific Advisory Committee Nurse and Advanced Practice subcommittee from 2015-2017. She was recognized by the American Gastroenterology Association with the Bridges to Excellence Award for quality care for Inflammatory Bowel Disease patients. She is a current member of the Association of Oklahoma Nurse Practitioners and the American Association of Nurse Practitioners. Amber joined Norman Gastroenterology Associates in 2017.