Clifford A. Bloch, MD graduated from the University of Witwatersrand Medical School in 1976, where he received his MD degree and then underwent a 1 year internship in Internal Medicine and Surgery/Anesthesiology followed by his Pediatric residency in Johannesburg, South Africa. He completed a 3 year fellowship in Pediatric Endocrinology and Metabolism in Cincinnati, Ohio. He was a member of full-time faculty at Children's Hospital and the University of Colorado School of Medicine for 5½ years before commencing private practice in 1992. Dr. Bloch is a Clinical Professor at the University of Colorado School of Medicine, a member of the State Committee for Newborn Screening, and a member of numerous societies, including the American Academy of Pediatrics, The Pediatric Endocrine Society, The Endocrine Society, The Colorado Society for Endocrinology and Metabolism, and the Society for Pediatric Endocrinology of the Rocky Mountains. He has served as an executive on the LWPES Professional Affairs Committee and has chaired the National Pediatric Endocrinology Private Practice Committee. He serves on the Section of Endocrinology Executive Committee of the American Academy of Pediatrics. He is the author of several articles and is a reviewer for several medical journals. He is board certified in Pediatrics and Pediatric Endocrinology.


Sunil Nayak, MD performed his undergraduate studies at Duke University and graduated from the University of Virginia School of Medicine in 1990. He completed his pediatric internship and residency at Carolinas Medical Center in Charlotte, North Carolina, where he was Chief Resident. He completed his Pediatric Endocrine Fellowship training at the Children's Hospital of Pittsburgh in 1997. He is Board Certified in Pediatrics and Pediatric Endocrinology. Dr Nayak is a member of the American Academy of Pediatrics, The Lawson Wilkins Pediatric Endocrine Society, The Colorado Society for Endocrinology and Metabolism, and the Society for Pediatric Endocrinology of the Rocky Mountains. He has been recognized as one of Denver’s Top Docs by 5280 Magazine. He enjoys skiing, golfing and running.

Alicia Marks, DO is a Colorado native, who graduated with a BS degree from the Bob Jones University and graduated from the University of North Texas – Texas College of Osteopathic Medicine in 2004. She completed her pediatric internship and residency at Driscoll Children’s Hospital in Corpus Christi, Texas. She completed her Pediatric Endocrine Fellowship training at the Oregon Health & Science University in 2010. She is Board Certified in Pediatrics and Pediatric Endocrinology. She is a member of the American Academy of Pediatrics, The Lawson Wilkins Pediatric Endocrine Society, and The Endocrine Society. In her spare time, she enjoys traveling, SCUBA diving, knitting, and spending time with her family.

Jean Bessey, MPH,RD performed her undergraduate studies at California State University, Fresno, receiving a BS in Nutrition Science. She underwent a 1-year internship at the University of California, San Francisco, and went on to become a Registered Dietitian. She became a Certified Diabetes Educator and returned to graduate school at Loma Linda University to obtain an MPH degree, with an emphasis in Health Promotion and Education. Prior to joining PEA, she provided counseling and education at a large medical clinic of over 50 physicians in California.
She also works as a Certified Product Trainer for Medtronic Diabetes, training patients in the Denver area to use the insulin pump and continuous glucose monitor.
On her days off, you can find her skiing, snow shoeing, hiking, camping or biking with her husband, son, and Golden Retriever, Max.

Mark T. Trottier, CHA/PA-C. Mark spent his first 22 years living in New Hampshire before moving to Colorado in 1995. He received his Bachelor of Science in biology from the University of Colorado at Denver in 2001. He later attended the Child Health Associate/Physician Assistant (CHA/PA) program at the University of Colorado Health Sciences Center, graduating and receiving certification from the NCCPA (National Commission for Certification of Physician Assistants) in 2005. Mark then worked in primary care pediatrics providing general health care to children for more than 5 years before deciding to join Pediatric Endocrine Associates in October of 2011. In his leisure time, Mark enjoys music, outdoor activities, and spending time with his 2 daughters (Kaitlyn and Maya).

Natalie Bloch, Office Manager, BA (hon)(social work), BA (Elementary Education) Natalie received her social work degree from the University of the Witwatersrand, and her teaching diploma from Metro State College. She has been the office manager of Pediatric Endocrine Associates since its inception in 1992.