MEET OUR DOCTORS
Dedication. Expertise. Passion.
Meet our amazing doctors who prioritize and provide high quality care for all of our patients
Medical Professionals You Can Trust
Dr. Nausheen
Ali, M.D.
Dr. Nausheen B. Ali earned her medical degree from Nishtar Medical College and completed her Internship, Residency, and Nephrology Fellowship at LA County+USC Medical Center in Los Angeles. She is board certified in Internal Medicine and Nephrology and has been caring for patients with kidney disease and hypertension since 2000.
Dr. Ali serves as Medical Director of DaVita Anaheim Hills and the Peritoneal Dialysis Program at DaVita Anaheim West. She is dedicated to providing compassionate, patient-centered care, with a strong focus on prevention, early intervention, and education to help patients manage their kidney health as a team.
Dr. Steve Bui, M.D.
Dr. Steve Bui completed his undergraduate studies at the University of California, Riverside, and earned his medical degree from St. George’s University School of Medicine. He completed his Internal Medicine Residency at Alameda County Medical Center and his Nephrology Fellowship at Kaiser Permanente in Los Angeles.
Dr. Bui serves as Medical Director at DaVita Tustin Dialysis and DaVita Mainplace Dialysis in Orange, and is currently Chief of Staff at Orange County Global Medical Center. He is fluent in English, Spanish, and Vietnamese, with clinical interests in acute kidney injury, hypertension, electrolyte disorders, and dialysis management.
As a Southern California native, Dr. Bui enjoys traveling with his wife and two children. In his free time, he plays golf and tennis, and coaches his son’s tennis and basketball teams.
Dr. Cheung is originally from Texas. After receiving his undergraduate engineering degree from MIT, he attended medical school at the Baylor College of Medicine in his hometown of Houston, Texas. After completing his residency at Methodist Dallas Medical Center, he moved to California and was proud to serve our veterans at the VAMC La Jolla as an Assistant Clinical Professor of Medicine at UC San Diego until 2011. Since completing a nephrology fellowship at UC Irvine in 2013, Dr. Cheung has been a private practice nephrologist in north Orange County.
Dr. Cheung sees patients in the hospital, dialysis, and office settings. He is active in clinical research and areas of interest include chronic kidney disease, anemia, and home dialysis modalities. He is fluent in English and Mandarin Chinese.
In his spare time, he enjoys spending time with his wife and 3 children, traveling, cooking, as well as being an avid sports fan, especially of his long-suffering Houston Rockets.
Dr. Nirav
Gandhi, M.D.
Dr Gandhi grew up here in Southern California. After getting his undergraduate degree from UCLA, he attended medical school at Chicago Medical School. He returned to Southern California for his Internal Medicine Residency at Kaiser-Permanente in Los Angeles. He stayed at Kaiser and completed his Nephrology fellowship there as well. He joined Nephrology Medical Group of Orange County in 2005 (which became Southern California Kidney Consultants in 2018).
In addition to rounding at several hospitals and dialysis centers, he sees his office patients in the La Palma and Anaheim offices. He is active in clinical research and he is a teaching attending at the West Anaheim Internal Medicine Residency Program.
He is fluent in English, Spanish and partially fluent in Gujarati.
In his spare time, he enjoys spending time with his wife and children. His hobbies include traveling, playing tennis, attending his kids’ basketball and soccer games, and hopelessly cheering on his beloved UCLA Bruins.
Dr. Mohammad
Ismail, M.D.
Dr. Mohammad Ismail brings over 30 years of nephrology experience to Southern California Kidney Consultants, having joined the group in 2021.
​
He graduated from Dow Medical College in 1981. He completed his residency in Internal Medicine at the VA Long Beach and the University of California, Irvine Medical Center in 1990, followed by a fellowship in Nephrology at VA Long Beach and the UCI School of Medicine in 1992. Dr. Ismail has extensive experience in clinical research and has co-authored several peer-reviewed publications. He is board-certified in both Internal Medicine and Nephrology.
​
Dr. Ismail is dedicated to patient care, focusing on education and attentive listening to ensure patients feel supported and informed. He is also committed to giving back to the community through charitable endeavors.
​
He is fluent in English and Urdu/Hindi. In his free time, he enjoys spending time with his family, traveling, and watching sports.
Dr. Alexander
Cheung, M.D.
Dr. Ashish
Kalthia, M.D.
Dr. Ashish Kalthia is a board-certified nephrologist who joined Orange County Renal Medical Group, now part of Southern California Kidney Consultants, in 2010. He provides comprehensive care for patients with kidney disease, with special expertise in kidney transplantation.
​
Born and raised in Chicago, Illinois, Dr. Kalthia later moved to Southern California, where he earned his bachelor’s degree in Biological Sciences at the University of California, Irvine. He went on to graduate from the UCLA School of Medicine in 2000. He completed his residency in Internal Medicine at UCI Medical Center in 2003, followed by a Chief Residency year in 2004. He then pursued fellowship training in Nephrology at UCI, completing it in 2006 and remaining on faculty until 2010.
​
During his tenure at UCI, Dr. Kalthia participated in numerous clinical trials and served as Medical Director for the Division of Kidney and Pancreas Transplantation from 2006 to 2010. His clinical interests continue to include transplantation, in addition to chronic kidney disease and dialysis.
​
Dr. Kalthia is fluent in English and Spanish, allowing him to care for a diverse patient population. Outside of medicine, he enjoys spending time with his wife and two children, exercising, and traveling.
Dr. Paul Krasner is a founding physician of Southern California Kidney Consultants and has been serving patients in the region for over five decades.
​
Born in Philadelphia, Pennsylvania on October 18, 1940, Dr. Krasner earned his medical degree from Hahnemann Medical College (now Drexel University College of Medicine) in 1966. He completed his medical internship at Upstate Medical Center in Syracuse, New York, followed by a residency in Internal Medicine at the University of Pennsylvania from 1967 to 1969. Pursuing a subspecialty in nephrology, he trained as a fellow at Thomas Jefferson University from 1969 to 1970.
​
From 1970 to 1972, Dr. Krasner proudly served in the U.S. Army with the 82nd Airborne Division at Fort Bragg, North Carolina. Following his military service, he relocated to Southern California, where he entered private practice in 1972. He joined Nephrology Medical Group in 1974 and later became part of Southern California Kidney Consultants, where he continues to provide expert, compassionate kidney care.
With decades of clinical experience, Dr. Krasner is deeply committed to advancing nephrology care and improving the quality of life for his patients.
Dr. Jiten
Mehta, M.D.
Dr. Jiten Mehta is a board-certified nephrologist who joined Southern California Kidney Consultants in July 2022.
Raised in Walnut, California, Dr. Mehta completed his undergraduate studies at the University of California, San Diego in 2012. He earned his medical degree from Midwestern University, Arizona College of Osteopathic Medicine in 2017, followed by residency training in Internal Medicine at West Anaheim Medical Center. He went on to complete his fellowship in Clinical Nephrology at the UCLA David Geffen School of Medicine, Ronald Reagan Medical Center, in 2022.
​
Dr. Mehta is dual board-certified in Internal Medicine and Nephrology by the American Board of Internal Medicine (ABIM). His academic work includes publications in nephrology and nanotechnology, including case reports in Glomerular Diseases and Journal of Nanotechnology. He is also pursuing further training in healthcare innovation through an Artificial Intelligence in Healthcare certificate program at Stanford University.
​
Fluent in English, Spanish, Gujarati, and Hindi, Dr. Mehta values the ability to connect with patients from diverse backgrounds. Outside of medicine, he enjoys spending time with his wife, family, and friends. He is an avid traveler and recreational basketball player, with plans to expand his interests to pickleball and golf.
​
Dr. Mehta is dedicated to combining clinical expertise, academic curiosity, and compassionate care to improve outcomes for patients with kidney disease.
Dr. Tanzina
Nasreen, M.D.
Dr. Tanzina Nasreen is a board-certified nephrologist who joined Southern California Kidney Consultants in 2021.
Originally from Chittagong, Bangladesh, Dr. Nasreen earned her undergraduate degree from Chittagong College and her medical degree from Chittagong Medical College. She went on to complete her residency in Internal Medicine at Loma Linda University and pursued subspecialty training in Nephrology through fellowship at LAC+USC Medical Center.
​
Dr. Nasreen is board-certified in both Internal Medicine and Nephrology. She is fluent in Bengali, which allows her to serve and connect with a broader patient population.
​
Outside of medicine, Dr. Nasreen enjoys reading, traveling, and gardening. She has a particular passion for cultivating exotic and rare tropical plants. These interests bring her a sense of balance and joy outside of her clinical work.
​
Dr. Nasreen is committed to providing compassionate, patient-centered kidney care and helping her patients achieve the best possible health outcomes.
Dr. Ramani
Nathan, M.D.
Coming Soon!
Dr. Paul
Krasner, M.D.
Dr. Samir
Patel, M.D.
Dr. Samir Patel is a board-certified nephrologist who joined Southern California Kidney Consultants in 2024. He provides care for patients across Orange County in hospitals, clinics, and dialysis centers. His clinical interests include chronic kidney disease and hypertension.
​
Born in London, England, and raised in California, Dr. Patel completed his undergraduate education at the University of California, Riverside. He went on to earn both his medical degree and Ph.D. at the Medical University of Lublin in Poland. During this time, he conducted research at the Renal Research Institute in New York City, authoring several scientific publications as part of his doctoral thesis on the association of height and outcomes in dialysis patients using a global database.
​
Following his research and doctoral training, Dr. Patel completed his residency in Internal Medicine at St. Mary Medical Center in Long Beach and his fellowship in Nephrology at the University of California, Irvine.
​
Dr. Patel is fluent in both English and Spanish. Outside of medicine, he enjoys spending time with his wife and two sons, as well as hiking and traveling.
Dr. Asha
Ravikumar, M.D.
Asha R. Ravikumar, M.D. is a graduate of Northwestern University Medical School. She trained in Internal Medicine at Georgetown University Hospital and Nephrology at UCSF (University of California, San Francisco). Dr. Ravikumar is board certified in Internal Medicine and Nephrology.
Dr. Ravikumar has been practicing since 2009 in Orange County. She specializes in chronic kidney disease and end state renal disease. Dr. Ravikumar has a further interest in diabetes, hypertension, and metabolic syndrome. She is an associate professor of medicine at Western University of Health Sciences, and is involved with the West Anaheim Medical Center Internal Residency program. She serves on various Graduate Medical Education Committees and is the Performance Improvement Committee chair at West Anaheim Medical Center.
In addition to clinical practice, Dr. Ravikumar is a Medical Director of DaVita La Palma Dialysis Center and DaVita Fountain Valley Dialysis Center. She has served as a Medical Director for both facilities since 2012. Dr. Ravikumar is also involved in clinical research trials.
Dr. Ravikumar is a member of the American Society of Nephrology, Renal Physician Association, and American College of Physicians. She resides in Orange County with her husband and two children, and enjoys running, performance arts, and continuing education.
Dr. Sridhar
Reddy, M.D.
Sridhar Reddy was born and raised in Wisconsin. He received undergraduate and medical degrees from the University of Wisconsin in Madison. He met his wife in medical school and they both completed their residencies in Philadelphia.
Dr. Reddy completed both his Internal Medicine and Nephrology residencies at Temple University. He reflects fondly on Philadelphia, particularly because of the excellent training. Dr. Reddy’s wife hails from California so with baby in tow they settled in Orange County in 2012.
Dr. Reddy joined Orange County Renal Medical Group in 2012. His primary hospital is St. Jude Medical Center. He has received several distinctions but he is most proud of the Physician of the Year award for Culture and Teamwork received in 2017. Dr. Reddy will be Chief of Medicine of St Jude in 2019.
His Nephrology interests are broad but some specifics include diabetic nephropathy, control of resistant hypertension and management of stone disease. He enjoys spending time with his wife and 3 kids.
Dr. Nancy
Said-Hernandez, D.O.
Dr. Nancy Said-Hernandez completed her Bachelors in Biology and Minor in Management at UC Irvine in 1998. She completed her Graduate Degree from California State Polytechnic University (2001) in Pomona where she achieved a Masters in Microbiology.
She attended Medical School at The College of Osteopathic Medicine of the Pacific (2005), followed by her Internal Medicine Residency (2008) and Nephrology Fellowship (2010) at UC Irvine Medical Center.
Her medical interest include Acid-Base Disturbances and Electrolyte Abnormalities. Her approach to patient care involves looking at the patient as a whole and trying to diagnose a systemic process, rather than focusing on individual symptoms.
Her hobbies include exercising, spending time with her children and helping with their activities.
Dr. Harmanjit
Singh, M.D.
Dr. Harmanjit Singh is a board-certified nephrologist who has been with Southern California Kidney Consultants since 2012. He provides care for patients across Orange County in hospitals, clinics, and dialysis centers. His clinical interests include chronic kidney disease, dialysis, and hypertension, with a focus on delivering compassionate and individualized treatment.
​
Originally from Amritsar, India, Dr. Singh earned his medical degree from Maulana Azad Medical College in New Delhi. He completed his residency in Internal Medicine at New York-Presbyterian Brooklyn Methodist Hospital and his fellowship in Nephrology at Harbor-UCLA Medical Center in Torrance, California.
​
Dr. Singh is fluent in English, Punjabi, and Hindi, which enables him to connect with and serve a diverse patient community.
Outside of medicine, he enjoys bicycling and traveling the world, always looking forward to exploring new places and experiences.
Dr. Rohini Singh, M.D.
Dr. Rohini Singh is a board-certified nephrologist with Southern California Kidney Consultants, where she has been caring for patients since 2021.
Dr. Singh grew up in the San Fernando Valley and completed her undergraduate studies at the University of California, Irvine. She went on to earn her Doctor of Osteopathic Medicine degree at Western University of Health Sciences, College of Osteopathic Medicine of the Pacific. She completed both her residency in Internal Medicine and her fellowship in Nephrology at Botsford Hospital in Michigan, where she developed a strong foundation in managing complex kidney diseases.
​
She is board-certified in Internal Medicine and Nephrology through the American Osteopathic Board of Internal Medicine (AOBIM). Dr. Singh is fluent in Hindi, which allows her to serve a diverse patient community with greater understanding and connection.
​
Outside of medicine, Dr. Singh enjoys spending time with her family and staying active with her children’s activities. She has a creative side and pursues hobbies such as cake decorating—specializing in hyper-realistic designs—and learning to sew. These passions provide her with a rewarding sense of balance between her professional and personal life.
​
Dr. Singh is dedicated to delivering compassionate, patient-centered care and is committed to helping her patients achieve the best possible kidney health.
Dr. Peter Sohn, M.D.
Dr. Peter Sohn is a dedicated nephrologist committed to providing comprehensive care for patients with kidney disease. Board-certified in both Internal Medicine and Nephrology, he brings a wealth of expertise from his extensive training and research in renal health. Currently practicing at Southern California Kidney Consultants in Garden Grove, California, since August 2022, Dr. Sohn focuses on managing complex conditions such as chronic kidney disease, dialysis, and hypertension, with a patient-centered approach informed by his background in medicine and public health.
Dr. Sohn's educational journey reflects a strong foundation in science and community health. He earned his Bachelor of Science in Biology and Bachelor of Arts in Sociology from the University of California, Irvine, in 2011. He then pursued his Doctor of Medicine and Master of Public Health at Drexel University in Philadelphia, graduating in 2017. His postgraduate training included an Internal Medicine Residency at the University of Southern California and Los Angeles County from 2017 to 2020, followed by a Nephrology Fellowship at the University of California, Irvine, completed in 2022.
Key credentials include:
Board Certification: American Board of Internal Medicine (ABIM) in Internal Medicine, Board Certification: ABIM in Nephrology, USMLE Step 1, Step 2 CS, Step 2 CK, Step 3.
​
Dr. Sohn is an active contributor to nephrology research, with publications in prestigious journals like Kidney International and Seminars in Nephrology. Notable works include "Intradialytic Hypotension: Is Timing Everything?" (2021) and "The Interplay Between Thyroid Dysfunction and Kidney Disease" (2021), exploring critical intersections in renal care. He has presented posters at national conferences, such as the American College of Physicians and Crohn's & Colitis Congress, on topics ranging from autoimmune hepatitis to inflammatory bowel disease outcomes in Hispanic populations.
Beyond clinical practice, Dr. Sohn has engaged in quality improvement projects, including reducing hospital-acquired pressure injuries and enhancing colonoscopy preparation education. His involvement in medical missions, such as post-earthquake relief in Haiti, underscores his commitment to global health equity. Patients appreciate his compassionate, evidence-based care, blending cutting-edge knowledge with personalized attention to improve quality of life.
Dr. Herbert Tiquia,
M.D.
Dr. Herbert Tiquia is a graduate of UC Davis Medical School. He trained in Internal Medicine and Nephrology at Kaiser Sunset in Los Angeles California. He has been practicing in Orange County since 2001.
His specialty interests include electrolyte management, blood pressure control and maximizing kidney preservation by empowering patients with insightful clinical guidelines. He has maintained his board certification in Nephrology. He is currently the Medical Director of DaVita Dialysis in Brea which has achieved a 5-Star CMS rating in 2016 and 2018.
His outside interests include playing tennis and racquetball. He enjoys travel and spending time with family.
Dr. Tania
Vashistha, M.D.
Dr. Tania Vashistha earned her medical degree from Bharati Vidyapeeth Medical University in Pune, India. She completed her Internal Medicine Residency at Resurrection Westlake Hospital in Chicago and her Nephrology Fellowship at UC Irvine Medical Center in 2015.
​
After fellowship, Dr. Vashistha practiced nephrology for five years in Denver, Colorado, before returning to Southern California in 2020 to join Southern California Kidney Associates. She is board certified in Nephrology and is dedicated to providing compassionate, evidence-based care to patients with kidney disease.
Outside of medicine, Dr. Vashistha enjoys Pilates, traveling, and spending time with her family, friends, and her three children. She is also a proud puppy parent and passionate about health, wellness, and exploring new cultures.
Dr. Henry Yuan, M.D.
Dr. Yuan received his undergraduate degree from the University of Texas at Austin. He attended medical school at Kaohsiung Medical University in Taiwan, where he obtained his Doctor of Medicine. After completing his Internal Medicine residency in Michigan, he completed his Nephrology fellowship training at The Johns Hopkins Hospital in Baltimore, Maryland.
Dr. Henry Yuan joined Southern California Kidney Consultants in 2018. He practices in the Anaheim and La Palma area, specializing in kidney diseases with a special interest in electrolyte disorders, cardio-renal syndrome, and hypertension.
​
Having grown up in South America, Dr. Yuan is fluent in Spanish and Portuguese, in addition to English, Mandarin Chinese, and Taiwanese.
Outside of medicine Dr. Yuan enjoys biking and traveling, is married and a proud father of a future PGA champion.