Providers

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All our professionals maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in the medical field. Read on to learn more about our staff's experience and training.

Jason Collins, M.D.

Dr. Jason Collins was born in Chicago, IL and is a graduate of the University of Michigan. He obtained his medical degree at the University of Illinois. His residency in Internal Medicine was completed at the University of Illinois Hospital, and he completed his fellowship training in Gastroenterology and Hepatology at Howard University.

 

Dr. Collins has had 15 years of experience in Gastroenterology and practiced in Georgia and Colorado before moving to Nevada. He is board certified by the American Board of Internal Medicine and a member of the American College of Gastroenterology. Dr. Collins is passionate about providing excellent care to his patients and dedicated to providing exceptional service to the community. 

 

Dr. Collins lives in South Reno with his two children and puppy, Sumi. When not at work, you can find Dr. Collins enjoying the outdoors , spending time with his kids, cooking, traveling or trying to learn a new song on guitar. 

Accepting New Patients:

• Dr. Collins is accepting new patients.

In Practice Since:

• 2007

Primary Specialty:

• Gastroenterology

Education:

• University of Michigan 1997
• University of Illinois College of Medicine 2001
• University of Illinois Hospital Internship and Residency Internal Medicine 2004
• Howard University Fellowship Gastroenterology 2007

Board Certifications:

• Gastroenterology: 2007, 2017

Professional Memberships:

• American Gastroenterological Association
• American College of Gastroenterology
• American Society for Gastrointestinal Endoscopy

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Harper Massey, D.O.

Dr. Massey is a native of the town of Fredericksburg, Virginia, a town steeped in history as George Washington's boyhood home. Pride in being the child of a physician – often recognized with gratitude by his patients – fostered a desire in her to follow in his footsteps. She studied neuroscience at Brown University in Rhode Island. She then spent a year researching single nucleic polymorphisms and localizing fetal DNA through maternal blood samples before earning a Master of Biomedical Science. She attended medical school at Virginia College of Osteopathic Medicine in Blacksburg, VA, before moving to Las Vegas for her Internal Medicine Residency and Gastroenterology Fellowship, where she was the chief fellow.

She was drawn to osteopathic medicine because of its focus on patient education and disease prevention as well as looking at the body as a unit of mind, body, and spirit. Gastroenterology afforded the opportunity to enter a field that balanced critical thinking with performing procedures that encompassed an interesting variety of related illnesses, a collegial collaboration with other specialists, the academic challenges and rigor for achieving the highest standards in innovation and techniques, and knowledge for state-of-the-art diagnosis and treatment ranging from emergency lifesaving care to chronic personalized long-term care.

Dr. Massey enjoys all aspects of gastroenterology and hepatology. Her special interests include inflammatory bowel disease, liver diseases, and colon cancer prevention as well as gastroesophageal reflux disease (GERD), eosinophilic esophagitis and women’s health. In addition, she performs Endoscopy (EGD), Colonoscopy, and Capsule Endoscopy.

She and her husband chose Reno/Carson City due to the opportunity for outdoor activities in the area. He is an avid hiker and skier while she grew up swimming and canoeing on the Chesapeake Bay. She also enjoys the performing arts, having grown up dancing with ballet, jazz, musical theater, and west African dance. They look forward to instilling a similar love for the outdoors and the arts with their family.

Accepting New Patients:

• Dr. Massey is accepting new patients.

In Practice Since:

• 2021

Primary Specialty:

• Gastroenterology

Education:

• Gastroenterology: 2017-2020 Valley Hospital Medical Center, Las Vegas, NV
• Residency: Internal Medicine: 2014-2017 Valley Hospital Medical Center, Las Vegas, NV
• Medical Education: Edward Via College of Osteopathic Medical School: 2010-2014 Blacksburg, VA

Board Certifications:

• Gastroenterology: 2021
• Internal Medicine: 2017

Professional Memberships:

• American Osteopathic Association
• American College of Gastroenterology
• Sigma Sigma Phi Honor Society

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Jason Kattenhorn, MSN, APRN, NP-C

Jason is a long-term resident of Northern Nevada since 1995. He started his nursing career in 2007 after graduating from Western Nevada College Nursing School and began working at Renown in the Intensive Care Unit (ICU). He then transferred to Carson Tahoe Regional Medical Center to work with Open Heart patients in the Cardiovascular Unit (CVU). During his eleven years working on the CVU, he gained an appreciation of caring for critically ill and complex patients and also obtained his Bachelor of Science in Nursing degree, followed by his Master's of Science in Nursing at University of Nevada Reno in the Adult Gerontology Acute Care Nurse Practitioner program.

 

Jason was drawn to gastroenterology during his clinical rotations in his Master’s program. Jason practices all aspects of general gastroenterology. He enjoys the continued care of complex and critically ill patients and welcomes his new role discussing ways that he can help patients achieve positive outcomes. 

 

Outside of work, he is spoiled by his wife, enjoys spending with his family, all sporting events, hiking around Lake Tahoe, and traveling.

 

In Practice Since:

2023

Education: 

Master of Science, Adult Gerontology Acute Care Nurse Practitioner: 2023

University of Nevada Reno Bachelor of Science in Nursing: 2007

Western Nevada College

Professional Affiliations:

American College of Gastroenterology member since 01/2023

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 Kimbrelle Pascua, MSN, APRN, NP-C

Kim recently moved to Reno from Las Vegas in July 2023. She started her nursing career in Sunrise Hospital and Medical Center in Las Vegas as an RN. After a few years, she pursued her Master of Science in Nursing at Chamberlain University College of Nursing. She is board certified through the American Academy of Nurse Practitioners Certification Board. She has been interested in many aspects of medicine. She has worked as an NP in the field of nephrology, acute care, ENT, and neurosurgery. She has always been interested in gastroenterology, so when she moved to Reno, she was able to finally join the field through Carson City Gastroenterology.

 

Kim immigrated to the US with her family from the Philippines in 2007. She moved to Las Vegas in 2013 to pursue her nursing career and met her husband there. They both love outdoor activities, hiking, and traveling. They have been attracted to the vastness of outdoor activities that Northern Nevada has to offer. She speaks Tagalog and English.

 

In Practice Since:

2018

 

Education:

Master of Science in Nursing - Family Nurse Practitioner: 2018 from Chamberlain University

Bachelor of Science in Nursing: 2011 from Manila Central University

 

Professional Affiliations:

American College of Gastroenterology member since 09/2023

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Theresa Rolniak, MSN, APRN, NP-C

Theresa is originally from Arkansas and earned her bachelor's degree in nursing in 2018. She started her nursing career in the Intensive Care Unit (ICU) in Fayetteville, Arkansas, then became a travel ICU nurse until joining the former Gastroenterology Consultants in 2021 as an endoscopy nurse. She has continued to work as a nurse at Carson Endoscopy Center while completing her master's degree through Samuel Merritt University, becoming a Family Nurse Practitioner in 2024. She is board certified through the American Nurses Credentialing Center (ANCC).

Theresa has a great interest and respect for Gastroenterology through her endoscopy and critical care experience. She looks forward to guiding and educating patients through complex health situations in a focused and realistic manner.

Theresa enjoys skiing, hiking, cooking, music, and being active with her Fiancé' and her dog. 

In Practice Since:

2024

Education:

Master of Science in Nursing, Family Nurse Practitioner, Samuel Merritt University Oakland, CA

Bachelor of Science in Nursing, University of Arkansas- Fort Smith, AR

Professional Affiliations:

American Nurses Association

Nevada Nurses Association

American Nurses Credentialing Center

National Comprehensive Cancer Network

Nevada Advanced Practice Nurses Association

American College of Gastroenterology

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Ana Turner, PA-C

Ana recently relocated to Carson City from San Antonio, Texas in November 2025. She earned her Bachelor’s degree in Nutritional Sciences from the University of Texas at Austin and went on to complete her Master of Physician Assistant Studies at the University of Texas Medical Branch in Galveston. She began her career in family medicine before finding her passion in gastroenterology, a field that allows her to combine her interests in nutrition, preventive health, and the pathophysiology of the gastrointestinal system. Ana enjoys the challenge of diagnosing and managing GI conditions and is dedicated to educating her patients and helping them improve their overall quality of life. She is also fluent in Spanish.

Outside of medicine, Ana enjoys spending time with her husband, family, their goldendoodle, and their community. Together, they are passionate about mission work. In her free time, Ana loves staying active through hiking, running, pickleball, kayaking, camping, and indoor rock climbing, as well as traveling and exploring all that Northern Nevada has to offer.