Physicians

All our physicians are board certified in gastroenterology and internal medicine. Please take time to get to know our doctors by clicking on their names to read more about their speciality, education and interests, or simply scroll down the page.

Brent N. Barranco, M. D.

Brent N. Barranco, MD, joined Gastroenterology Associates, N.A., P.C. in July 2003 and practices at our Brookwood location. He obtained his undergraduate degree from Auburn University and his medical degree from Tulane University. His internship, residency and fellowship were all performed at the University of Alabama at Birmingham Hospitals. Dr. Barranco is board certified in Internal Medicine and Gastroenterology.

Dr. Barranco is a member of the American College of Physicians, American College of Gastroenterology, American Gastroenterological Association, and the American Society of Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society.

Allison D. Bridges, M.D.

Allison Duke Bridges, MD joined Gastroenterology Associates of N.A., P.C. in September 2008 and practices at our St. Vincent’s East location. She obtained her undergraduate degree from Auburn University and her medical degree from the University of South Alabama. Her internship and residency were performed at the University of Wisconsin Hospital and Clinics in Madison, WI. Her fellowship was performed at the University of Alabama at Birmingham. During this time, she also obtained a Master of Science in Public Health focusing on Health Outcomes Research. Dr. Bridges is board certified in both Internal Medicine and Gastroenterology.

Dr. Bridges is a member of the American College of Gastroenterology, the American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy, the American Association for the Study of Liver Diseases, and the Alabama Gastroenterological Society.

Brian A.Brunson, M.D.

Brian A. Brunson, M.D., a Birmingham native, joined GANAPC in July 2012 and practices primarily at Shelby Baptist Medical Center. He has special interests in gastrointestinal oncology and pancreatic diseases, and performs endoscopic ultrasound (EUS) procedures at Brookwood Medical Center and St. Vincent’s East in addition to Shelby BMC. He obtained his undergraduate degree from Auburn University and his medical degree from the University of Alabama at Birmingham. Dr. Brunson performed his internship and residency at the University of Alabama Hospital in Birmingham, and his GI fellowship was completed at the Medical University of South Carolina in Charleston, SC. He is board certified in both Internal Medicine and Gastroenterology (exam completed 10/3/12).

Dr. Brunson is a member of the American Gastroenterological Association, the American Society of Gastrointestinal Endoscopy, the ASGE EUS special interest group, the American College of Gastroenterology, and the Alabama Gastroenterological Society.

Gregory L. Champion, M.D.

Gregory L. Champion, MD joined Gastroenterology Associates, N.A., P.C. in July 1994 and practices at our Brookwood location. He obtained his undergraduate degree from the University of Alabama and his medical degree from the University of South Alabama. He performed his internship, residency, and fellowship at the University of Alabama at Birmingham. Dr. Champion is board certified in both Internal Medicine and Gastroenterology.

Dr. Champion is a member of the State Medical Association, American College of Gastroenterology, American Gastroenterological Association, American Society of Gastrointestinal Endoscopy, the Crohn’s and Colitis Foundation of America, and the Alabama Gastroenterological Society.

John P. Day, M.D.

John P. Day, MD joined Gastroenterology Associates, N.A., P.C. in July 1992 and practices at our Shelby location. He obtained his undergraduate degree from the United States Naval Academy and his medical degree from the Medical College of Georgia. He performed his internship, residency and fellowship at the University of Alabama at Birmingham. Dr. Day is board certified in both Internal Medicine and Gastroenterology.

Dr. Day is a member of the State Medical Association, American Medical Association, American College of Physicians, American College of Gastroenterology, American Gastroenterological Association, the American Society of Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society.

W. Timothy Denton, M.D.

W. Timothy Denton, MD, is the president of Gastroenterology Associates, N.A., P.C. and joined Gastroenterology Associates, N.A., P.C. in June 1984. He practices at our Brookwood location. He obtained both his undergraduate and medical degree from the University of Mississippi. His internship, residency, and fellowship were all performed at the Medical University of South Carolina. Dr. Denton is board certified in both Internal Medicine and Gastroenterology.

Dr. Denton is President of the Alabama Gastroenterological Society, and is a member of the State Medical Association, American Medical Association, American College of Gastroenterology, American Gastroenterological Association, the American Society of Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society. He is also a member of the Crohn’s and Colitis Foundation of America and received their J. Marshall Garrett Medical Achievement Award in 2002.

Miles E. Gresham, M.D.

Miles E. Gresham, MD joined Gastroenterology Associates, N.A., P.C. in July 1986 and practices at our St. Vincent’s East location. He obtained his undergraduate degree from the University of Alabama and his medical degree from the University of Alabama at Birmingham. Dr. Gresham performed his internship and residency at Carraway Methodist Medical Center in Birmingham and his fellowship at the Medical University of South Carolina. Dr. Gresham is board certified in both Internal Medicine and Gastroenterology.

Dr. Gresham is a member of the State Medical Association, American Medical Association, American College of Gastroenterology, American Gastroenterological Association, the American Society of Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society.

William H. Halama, M.D.

William H. Halama, MD joined Gastroenterology Associates, N.A., P.C. in October 1999 and practices at our Brookwood location. Prior to this date, Dr. Halama was in practice with Gastrointestinal Medical Specialists of North Alabama, P.C. Dr. Halama obtained his undergraduate degree from the University of Alabama and his medical degree from the University of Alabama at Birmingham. He performed his internship and residency at The Baptist Medical Centers in Birmingham, Alabama and his fellowship at Wayne State University in Detroit, Michigan. Dr. Halama is board certified in both Internal Medicine and Gastroenterology.

Dr. Halama is a member of the State Medical Association, American College of Gastroenterology, the American Gastroenterological Association, and the Alabama Gastroenterological Society.

Robert D. Loudon, M.D.

Robert D. Loudon, MD joined Gastroenterology Associates, N.A., P.C in July 2006 and practices at our Shelby location. Dr. Loudon obtained his undergraduate degree from Louisiana State University and his medical degree from Louisiana State University Medical Center. He performed his internship and his residency at the University of Alabama Hospital in Birmingham. Dr. Loudon performed his Hepatology/Liver Transplant fellowship at the Mayo Clinic in Jacksonville, Florida and his Gastroenterology fellowship at the University of Louisville Medical Center. Dr. Loudon is board certified in both Internal Medicine and Gastroenterology.

Dr. Loudon is a member of the American Gastroenterological Association, the American Society of Gastrointestinal Endoscopy, the American College of Gastroenterology, and the Alabama Gastroenterological Society.

Robert D. Marks, M.D.

Robert D. Marks, MD joined Gastroenterology Associates, N.A., P.C. in June 1996 and practices at our Shelby location. Prior to this date, Dr. Marks was an assistant professor of medicine in the division of Gastroenterology and Hepatology at the University of Alabama at Birmingham. Dr. Marks obtained his undergraduate degree from Mississippi State University and his medical degree from Meharry Medical College. He performed his internship at St. Mary’s Hospital and his residency and fellowship at the University of Alabama at Birmingham. In 1996 Dr. Marks completed his M.P.H. at Yale University School of Epidemiology and Public Health. He is board certified in both Internal Medicine and Gastroenterology.

Dr. Marks is a member of the State Medical Association, American Medical Association, American College of Physicians, American College of Gastroenterology, American Gastroenterological Association, American Society of Gastrointestinal Endoscopy, the Alabama Gastroenterological Society, and the Society for Clinical Epidemiology and Health Care Research.

Lindsay South Robison, M.D.

Lindsay South Robison, MD joined Gastroenterology Associates of N.A., P.C. in September 2011 to practice at our Brookwood location. She obtained her undergraduate degree from Washington and Lee University and her medical degree from the University of Alabama School of Medicine. She performed her internship, residency, and gastroenterology fellowship at the University of Alabama at Birmingham Hospitals. She was the recipient of a 2010 GI Fellows’ Research Award in Inflammatory Bowel Disease to study family planning issues in patients with inflammatory bowel disease. Dr. Robison is board certified in both Internal Medicine and Gastroenterology.

Dr. Robison is a member of the American College of Gastroenterology, the American Association, the American Society for Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society.

Bradley A. Rubery, M.D.

Bradley A. Rubery, MD joined Gastroenterology Associates, N.A., P.C. in July 2002 and practices at our Shelby location. He obtained his undergraduate degree from the University of Alabama at Huntsville and his medical degree from the University of Alabama at Birmingham. He performed his internship at Greenville Memorial Hospital and his residency and fellowship at the University of Mississippi Medical Center. Dr. Rubery is board certified in both Internal Medicine and Gastroenterology.

Dr. Rubery is a member of the State Medical Association, American Medical Association, American Gastroenterological Association, and the American Society of Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society.

Robert A. Shaffer, M.D.

Robert A. Shaffer, MD joined Gastroenterology Associates, N.A., P.C. in July 2005 and practices at our St. Vincent’s East location. He obtained his undergraduate degree from Troy State University and his medical degree from the University of Alabama at Birmingham. His internship and residency were performed at Carolinas Medical Center and his fellowship performed at the University of Arkansas for the Medical Sciences. Dr. Shaffer is board certified in both Internal Medicine and Gastroenterology.

Dr. Shaffer is a member of the American College of Physicians, American College of Gastroenterology, American Gastroenterological Association, the American Society of Gastrointestinal Endoscopy, and the Alabama Gastroenterological Society.