Healthcare Services and Programs


Dr. Thomas SonnastineThomas E. Sonnanstine, MD, FACS, FASMBS

Fellowship-trained and Board-Certified in Bariatric/Advanced Laparoscopy/General Surgery
Associate Member of the American College of Surgeons
Member of the Society of American Gastrointestinal, Endoscopic and Lapaproendoscopic Surgeons

A native of Marion, Ohio, Dr. Sonnanstine is a graduate of Case Western Reserve University in Cleveland and Northeastern Ohio Medical University, near Akron. He served his residency at OhioHealth Riverside Methodist Hospital and completed fellowship training in minimally invasive bariatric surgery at Tufts Medical Center in Boston.

Now having practiced for 9+ years, Dr. Sonnanstine has performed more than 2,500 bariatric operations. He is an internationally and nationally recognized educator, having performed or taught weight-loss procedures in eight countries and 26 states.

Dr. Sonnanstine is married and the father of three children, two of whom were born at Riverside Methodist Hospital. He returns to Riverside Methodist as the Medical Director of Bariatric Surgery and lead bariatric surgeon among the team of dietitians, psychologists, exercise physiologists and other specialists at OhioHealth Surgical and Medical Weight Management.

Dr. Sonnanstine is a specialist in laparoscopic bariatric surgeries, including gastric bypass, adjustable gastric band and gastric sleeve procedures. He brings his special interest in high-risk patients and revisions to the OhioHealth bariatric team, offering care to patients with complications or failed surgery from other programs.

Dr. Nirav RanaNirav R. Rana, MD, FACS

Board Certification: General Surgery
Medical School: Northeastern Ohio Universities College of Medicine
Residency: St. Vincent’s Catholic Medical Center, Manhattan
Fellowship: Cedars-Sinai Medical Center, Los Angeles

Dr. Rana is a bariatric surgeon who specializes in minimally-invasive weight loss surgery including: Laparoscopic Roux-en-Y Gastric Bypass, Sleeve Gastrectomy, Gastric Banding, and Revisional Bariatric Surgery. He is joining Dr. Sonnanstine at OhioHealth Surgical Specialists and OhioHealth Weight Management to treat patients during their weight loss journey.

Dr. Rana is a member of several professional organizations including the American College of Surgeons, American Society of Metabolic and Bariatric Surgery (ASMBS), and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES). Dr. Rana is committed to the advancement of laparoscopic bariatric surgical techniques and patient education. He is also happy to be back treating patients in his hometown.


Julie Stermer Cantrell, MDJulie Stermer Cantrell, MD

Board Certified by the American Board of Obesity Medicine
Board Certified by the American Board of Family Medicine
Medical School: The Ohio State University College of Medicine
Residency: Riverside Methodist Hospital, Columbus, Ohio
Member of the American Academy of Family Physicians
Member of the Ohio Academy of Family Physicians

Dr. Cantrell oversees patient management and program development for OhioHealth Medical Weight Management. She meets with patients one-on-one to monitor their progress, lab results and overall health.

In addition to her work in medical weight management, Dr. Cantrell performs cardiac stress testing and medically manages patients enrolled in The McConnell Heart Health Center's cardiac rehabilitation program. She also manages patient care in the anticoagulation clinic and supervises stress testing for new Center members. 

Dr. Cantrell lives in Worthington with her husband and three children.

"The greatest benefit that results from weight loss is not how you look in the mirror. It's the many ways your health will benefit. Weight loss can improve blood pressure, cholesterol, diabetes and reduce heart disease risk. It can treat GERD, sleep apnea and arthritis pain. It can help a person to live longer and feel better on fewer medications."

Tom Houston, MDTom Houston, MD

Tom Houston, MD, is a graduate of the University of Mississippi School of Medicine. He completed his family medicine residency at University Hospitals in Jackson, Mississippi, where he was chief resident. After a year of private practice, he moved to Columbus in 1981 and was assistant professor of family medicine at Ohio State. Over the next 10 years, he had academic appointments at medical schools in Georgia and Kansas.

From 1990-2003, he directed the initiatives in preventive medicine and public health at the American Medical Association in Chicago. He was then recruited as the Jim Finks Endowed Professor in Health Promotion at LSU School of Public Health in New Orleans. He came to McConnell in 2005 following Hurricane Katrina. He is certified by the American Board of Family Medicine and is a Fellow of both the American Academy of Family Physicians and the American College of Preventive Medicine. He is a member of the Board of the Ohio Academy of Family Physicians and is clinical professor of Family Medicine and Public Health at OSU.

 Scott Merryman, MDScott Merryman, MD 

Scott Merryman, MD is the clinical director of cardiovascular risk management at the McConnell Heart Health Center Cardiovascular Disease Prevention and Lipid Clinic. He specializes in evaluating and treating people with elevated blood lipid levels to lower their risk for heart and vascular disease. His lipid clinic at McConnell uses advanced testing methods to obtain accurate and predictive information used to guide treatment, with the goal of preventing events such as heart attack or stroke.

Dr. Merryman is board-certified in clinical lipidology and family medicine. An area of interest for him is behavioral medicine, and working collaboratively with patients to achieve their goals. Dr. Merryman attended The Ohio State University College of Medicine and completed his residency at St. Joseph Hospital in Denver, Colorado. He is a member of the National Lipid Association, the American Academy of Family Physicians and the Ohio Academy of Family Physicians. He has been named one of America’s Best Doctors by U.S. News & World Report.


Dorienna M. Alfred, PhDDorienna M. Alfred, PhD

Licensed Psychologist in Ohio
Graduated from Indiana University with a PhD in Counseling Psychology with concentration in Applied Health Science
Fellowship: University of Missouri Counseling Center and Auburn University Department of Counseling Psychology and Counselor Education
Internship: University of Illinois, Urbana-Champaign Counseling Center
Member of the American Psychological Association
Member of the Black Women's Health Imperative
Member of the Ohio Psychological Association

Dorienna M. Alfred, PhD, is a staff psychologist at OhioHealth Surgical and Medical Weight Management. She provides psychological assessments for surgical patients and collaborates with physicians and nutritionists regarding recommendations for each patient's success in the program. Dorienna also provides psychological assessments as well as outpatient psychotherapy to patients in the medical weight treatment program.

Dorienna received training at the American Society of Metabolic and Bariatric Surgery (June 2012); The Ohio State University Addiction Studies Institute (August 2011); and the Center for Balanced Living at The Ohio State University for dialectical behavioral therapy and eating disorders (April 2011).

When she's not at work, Dorienna enjoys reading, exercising and spending time with family and friends.

"I try to reinforce with my patients that I know there is a medical necessity for their weight loss, a reason why they need it, and that I am here to support them and make sure they're prepared for the journey. It is my belief that with adequate support, optimal coping skills, knowledge and a commitment to better health, patients can achieve their wellness goals."


Joann Schaumburg, MS, RD, LDJoann Schaumburg, MS, RD, LD

Graduated from The Ohio State University with a Master of Science in Medical Dietetics and specialization in Clinical Nutrition and a Bachelor of Science in Medical Dietetics
Member of the American Dietetic Association
Member of the Weight Management Dietetic Practice Group

Joann Schaumburg is a Registered Clinical Dietitian at OhioHealth Surgical and Medical Weight Management working one-on-one with surgical and medical weight management patients. She provides nutritional assessment, education, planning and counseling.  Joann also develops patient education materials on nutrition topics and teaches nutrition classes. She's been a clinical dietitian at The McConnell Center for more than 10 years. Joann lives in Galena, Ohio.

"I try to have patients let go of negativity surrounding their eating habits and help them with a more positive outlook. I tell them, 'I'm going to help you find foods you can enjoy just as much as burgers and fries and pizza but that are better for you.' It's a process that involves a lot of trial and error and experimenting with new things but, in the end, they find foods they enjoy that are healthy."

Kristi Ann Highley, MS, RD, LDKristi Ann Highley, MS, RD, LD

Graduated from the University of Florida with a Master's of Science in Nutrition and Michigan State University with a Bachelors of Science in Dietetics
Certificate of Training in Adult Weight Management from the American Dietetic Association

Kristi is a Registered Clinical Dietitian at OhioHealth Surgical and Medical Weight Management working one-on-one with surgical patients. She provides nutritional assessment, planning, education and counseling. She works closely with her bariatric patients to help them understand the changes they need to make for their weight-loss journey to be safe and succeed as well as to support them in their nutritional education. Kristi has more than 25 years of experience in the field of nutrition and weight management. She lives in Canal Winchester, Ohio.

"I struggled all through adolescence and college with my own weight issues. During college, I switched my major to studying nutrition and exercise physiology so I could figure out why I couldn't win the battle. That's when light bulbs went off. I know first-hand how important lifestyle change is for successful weight loss - and how hard it is to achieve - and it's my passion to help others make this change."