Karl Hempel, M.D., F.A.C.P.
A founding member of San Antonio Medical Associates, Dr. Hempel is a graduate of the University of Cincinnati. After receiving his medical degree, he completed his residency and internship at the University of Oregon. Dr. Hempel then came to San Antonio for a Rheumatology Fellowship at the University of Texas Health Science Center.
He is licensed by the American Board of Internal Medicine and is also board certified in Rheumatology specializing in rheumatoid arthritis and other rheumatogical diseases. Dr. Hempel is a member of the American College of Physicians, American College of Rheumatology, Texas Medical Association, and Bexar County Medical Society.
Dr. Hempel was a Clinical Professor of Medicine at the University of Texas Health Science Center and also served in the National Guard.
Charles Briseño, M.D.
Dr. Briseño is a native San Antonian and a graduate from the University of Texas Southwestern Medical School in Dallas, Texas. He completed his internship and residency in San Antonio. He also served in the U.S. Navy as a Lt. Commander.
Dr. Briseño is board certified by the American Board of Internal Medicine and belongs to many local and national professional organizations, including the American College of Physicians, Texas Medical Association, and Bexar County Medical Society.
He joined San Antonio Medical Associates in 1975, where he specializes in internal medicine. Dr. Briseño serves as Medical Director of Nix Home Care. As a past instructor at the University of Texas Health Science Center he guided aspiring physicians in an “Introduction to Clinical Medicine” course.
Dr. Briseño is fluent in both English and Spanish.
Dina Goytia-Leos, M.D., F.A.C.P.
Dr. Goytia-Leos joined San Antonio Medical Associates in 2002 and holds a specialty in Internal Medicine. She is also a research investigator for Sonterra Clinical Research, where she focuses primarily on diabetes research.
She graduated from Howard University College of Medicine in Washington, D.C. and completed her internal medicine internship and residency at the University of Texas Health Science Center in San Antonio. She is currently the Chairperson for the Department of Medicine at Nix Health.
Dr. Goytia-Leos is board certified by the American Board of Internal Medicine and the Texas State Board of Medical Examiners. She is a member of the Bexar County Medical Society, and American College of Physicians. Dr. Goytia-Leos is fluent in both English and Spanish.
Uma C. Nair, M.D.
Dr. Nair, who joined San Antonio Medical Associates in 2012, holds a degree in medicine from the University of Texas Health Science Center and a Ph.D in pharmacology from the University of Texas Graduate School of Biomedical Sciences.
After graduation, Dr. Nair completed her internship in internal medicine, as well as her residency in internal medicine, at the University of Texas Health Science Center.
Dr. Nair is board certified by the American Board of Internal Medicine and is certified in both Basic Cardiac Life Support and Advanced Cardiac Life Support. Dr. Nair currently serves as a member of the Society of Hospital Medicine, Texas Medical Association and Bexar County Medical Society.
Carlos Carretero, M.D.
Dr. Carretero has recently joined San Antonio Medical Associates and holds a degree in medicine from Universidad Autonoma de Guadalajara. His clinical work was performed at New York Medical College, St. Vincent’s Hospital, New York, New York, interning with the Department of Veteran Affairs Medical Center in San Juan, Puerto Rico and completed his residency at Damas Hospital-Ponce School of Medicine, Puerto Rico.
Dr. Carretero is board certified by the American Board of Internal Medicine and has served as an Internal Medical Consultant, providing inpatient and outpatient care.
Dr. Carretero is fluent in Spanish, English, Hebrew, and Italian.
Location and Directions
Nix Medical Clinic
414 Navarro St., Suite 703
San Antonio, TX 78205
Phone: (210) 224-4811
The Nix Medical Clinic, located at 414 Navarro St., offers patients a convenient location to see their internal medicine physician. A team of skilled doctors and nurses provide personalized care in an intimate environment.