Our Doctors

and medical staff!


Doctor of Audiology

Renee L.G. Koffend has a Doctorate Degree in Audiology. She is the first Chamorro Audiologist. Dr. Koffend is nationally certified and a member of the American Speech-Language & Hearing Association. She completed her clinical fellowship year in 1990 in Milwaukee, Wisconsin. Dr. Koffend is licensed to practice in Guam and in the State of Illinois. She was previously the senior audiologist at the prestigious Chicago ENT. Dr. Koffend is a consultant to the Guam and Federate States of Micronesia EHDI Programs (Early Hearing Dectection and Invervention Programs ). She performs diagnostic hearing evaluations for children that fail newborn hearing screening. Dr. Koffend is the daughter of Vicente M. and Maria C. Leon Guerrero. Her mother is the famous Tita of Tita’s Bakery and Tita’s Guguria. When you visit Guam Hearing Doctors, you will leave with a tasty bakery treat!


Doctor of Otolaryngology

Jerry R. Castro is an American Board of Otolaryngology certified doctor. He specializes in treatment and surgery for diseases of the ear, nose and throat. Dr. Castro has completed two fellowships: Head and Neck Oncologic Surgery at Memorial Sloan-Kettering Cancer Center (2007) and Microvascular Reconstructive Surgery of the Head and Neck at Beth Israel Medical Center (2014). Both Dr. Koffend and Dr. Castro are Chamorro, born and raised on Guam.


Medical Assistant

Grace Nivera received her medical assistant degree from the Guam Community College in 2008. She has never stopped learning and has been in the hearing industry for over 12 years. Grace is familiar with the challenge and struggles of hearing loss and its impact on communication and learning. She is able to establish immediate rapport with patients so that they are comfortable in our clinic. She is an immigrant and fluent in Tagalog. Grace has been working with Dr. Koffend since 2014 and is valuable to the day-to-day operations of Guam Hearing Doctors. She is a mother of a toddler and comes from a close family. Her love for family makes her a perfect fit!


Patient Service Coordinator

Odelia "Daeyah" has been with Guam Hearing Doctors since October of 2018 as a Patient Service Coordinator. She has five years experience within the medical field and a certified EMT-B with the National Registry of Emergency Medical Technicians. A daughter to Filipino immigrants. Daeyah was born and raised on Guam, yet proficient in Tagalog. Daeyah is married with two children and read to assist you with all your hearing needs.