Meet the Fellows


Third-year Fellows

Jennifer Ni, MD

Medical School
University of Pittsburgh School of Medicine

Pediatrics Residency
University of Texas Southwestern Medical Center, Dallas

I grew up mainly in the Bay Area of California, attending UC Berkeley for undergraduate (Go Bears!) with a major in Bioengineering. After a gap year working at a biotech start up, I traveled to the East Coast for medical school at the University of Pittsburgh, and then back to my birth state of Texas for residency at UT Southwestern. During my experiences in medical school and residency, I discovered that I enjoyed the logic of thinking through signaling pathways to understand the pathophysiology of endocrine disorders. In the future, I hope to combine my background in engineering with my passion for medicine to advance the field of endocrinology, especially in diabetes management. I am very excited to return to the Bay Area for fellowship in Pediatric Endocrinology.

Outside of the hospital, I enjoy baking sweet treats, trying new restaurants, and running.


Luisa Valenzuela Riveros, MD

Medical School
University of California, Davis School of Medicine

Pediatrics Residency
Lucile Packard Children's Hospital, Stanford University

I was born and raised in Bogotá, Colombia, I moved to the Central Valley of California in my early teens. Ever since then, California has been my second home. I majored in Neurobiology, Physiology and Behavior at UC Davis. I continued my medical education at UC Davis as part of the San Joaquin Valley PRIME program which allowed me to do my clinical years in the Central Valley. This experience allowed to delve deeper in the unique health challenges rural families face and cultivated my passion for pediatrics. I completed pediatrics residency at Stanford where I was part of the medical education scholarly concentration and LEAD (Leadership Education in Advancing Diversity). 

My interests include medical education, research in healthcare delivery, disparities in management of endocrinological disorders in vulnerable communities, and pediatric bone health.

Second-Year Fellow

Mindy Lee, MD, PhD

Medical School
University of Texas Southwestern Medical School

Pediatrics Residency
Lucile Packard Children's Hospital, Stanford University

I was born in Taipei, Taiwan, and moved to the US when I was 11 years old. I have always been interested in biology, technology, and medicine, so I pursued a degree in bioengineering as an undergraduate student at the University of Pennsylvania. Later, I obtained a PhD studying autophagy, which is a cellular degradation pathway with important implications in metabolic disorders, neurodegenerative diseases, cancers, and immunity. Throughout my medical training, I developed a particular interest in diabetes technology. I realized that although the pathophysiology of type 1 diabetes is well understood and we can treat patients with life-saving insulin during acute hospitalizations, the long-term glycemic control for pediatric patients with diabetes remains inadequate. Additionally, the quality of life for patients and their family is often compromised due to the difficulty of adhering to strict monitoring and treatment regimen. My current research interest is to advance the application of diabetes technology to improve clinical care through various systems improvement and clinical research projects.

Outside of work, I enjoy spending time outdoors with my husband and our dog, playing board games, and cooking for friends.


Aaron Misakian, MD

Medical School
University of Washington School of Medicine

Pediatrics Residency
Children's Hospital of Philadelphia

I grew up in a rural community near the foothills of the Central Valley of California. At the ripe age of 17, I left for the East Coast and graduated with a BFA in Acting from NYU. After a brief TV and film career, I attend the Old Globe Theatre and University of San Diego where I earned an MFA in Acting with a concentration in Shakespeare. After writing a movie about a fictional neonatologist, I switched careers and decided to attend medical school. I graduated from University of Washington Medical School, where I conducted research in immunology and completed the Native American and Underserved Pathways. I also led several community advocacy projects focused on LGBTQ+ health and HIV while in the Pacific Northwest. In 2021, I completed a residency in categorical pediatrics at the Children’s Hospital of Philadelphia. Aside from the heavy clinical load required by any residency, I conducted research in bone health with children with Differences in Sexual Development (DSDs) and created an LGBTQ+ educational curriculum for residents. I am now pursuing a double combined fellowship in Pediatric Endocrinology and Adolescent Medicine focusing on transgender and gender diverse children and adolescents. My current research is dedicated to quantifying functional strength and better understanding bone health in trans adolescents who are using Hormonal Replacement Therapy (HRT). 

For fun, I have 2 obese cats and love to surf. Oh, and I love spending time with my grandma. 

First-Year-Fellows

Rebecca Jo Johnson, MD

Medical School
University of Nebraska College of Medicine

Pediatrics Residency
Lucile Packard Children's Hospital, Stanford University

I am so incredibly excited to be starting my Pediatric Endocrinology fellowship at Stanford this summer.  I had the privilege to complete my pediatric residency training at Stanford and the Bay Area quickly felt like home, and I could not feel more honored to continue my training here.  I was born and raised in Nebraska, completed college in New York and ultimately returned to Nebraska for medical school.  I met my husband, Kaleb, in medical school – he is thrilled to also join the Stanford family and is starting his Nephrology fellowship here this summer! 

Throughout my residency training I became involved in various clinical and quality improvement projects that I hope to continue during my fellowship training.  I am currently working on a study that is exploring transgender-specific interventions within school systems and how it relates to perceptions of support and acceptance to transgender youth.  I was also involved in a quality improvement project targeting the safe administration of inpatient short-acting insulin and was proud that it resulted in the creation of a clinical pathway for short-acting insulin ordering and administration, which was approved by the Packard Clinical Pathway Committee and is currently linked to an order set within EPIC! 

During my free time I enjoy traveling with my husband – we love exploring California and discovering all the wonderful hikes that the state has to offer!  We also have a border collie, Addie, who accompanies us on all of our adventures.  I also love cooking, baking, reading and spending time with family and friends. 


Hector Ortega, MD

Medical School
University of Miami Leonard M. Miller School of Medicine,

Pediatrics Residency
University of Miami/Jackson Health System

Most of my time growing up was spent in South Florida until college when I went to Florida State University and majored in Biology. During my gap year, I spent a year in Tallahassee providing behavior therapy to children with various developmental needs before I was accepted for medical school at the University of Miami (The U) where I also stayed for residency. Through my medical training I found I had a passion for adolescent care as well as the interface between patients and technology, making Pediatric Endocrinology at Stanford the perfect fit. My professional interests include behaviorism, informatics, and health equity.

Outside of medicine, I enjoy reading sci-fi/fantasy, playing Ultimate frisbee, and feeding my laner.

Fellowship Program

Recent Graduates

2021

Holly Cooper, MD, MS - Pediatric Endocrinologist at Mary Bridge Children's Hospital

2021

Walter Zegarra, MD - Pediatric Endocrinologist at Johns Hopkins All Children’s Hospital

2020

Ananta Addala, DO, MPH - Instructor, Pediatric Endocrinology and Diabetes at Stanford University

2019

Rayhan Lal, MD - Assistant Professor, Pediatric Endocrinology and Diabetes and Adult Endocrinology, Gerontology and Metabolism at Stanford University

2019

Maria Chang, MD - Pediatric Endocrinologist at Santa Clara Valley Medical Center