Meet the Team

Dr. Arie Ganz

Dr. Arie Ganz

Dr. Arie Olivo Ganz completed his Internal Medicine training at Lincoln Medical and Mental Health Center in Bronx, New York and his Nephrology fellowship at Metropolitan Hospital, New York Medical College in New York.

Born and raised in El Salvador, Dr. Ganz is fluent in English and is a native Spanish speaker. In his free time, he enjoys outdoor activities, traveling and spending time with friends and family.

Dr. Melvin Ooi

Dr. Melvin Ooi (Wei Boon)

Dr. Melvin Ooi (Wei Boon) completed his Internal Medicine training at Baystate Medical Center/Tufts University in Massachusetts prior to pursuing his Nephrology fellowship at Oregon Health and Science University in Portland, OR.

Originally from Malaysia, Dr. Ooi completed his medical school in Canada before to moving to the United States. He is fluent in English, Malay, Cantonese and Mandarin. He is an outdoor enthusiast and enjoys traveling in his leisure time.

Dr. Valerie Tan

Dr. Valerie Tan

Dr. Valerie Tan completed her Internal Medicine training at Roger Williams Medical Center in Rhode Island and her Nephrology fellowship at Baylor University Medical Center in Dallas, Texas.

Originally from the Philippines, Dr. Tan is fluent in Filipino and English. She moved to the United States with her husband who is an Internal Medicine Primary Care physician. Dr. Tan now resides on Oahu with her family. She enjoys spending time with family, loves to travel and explore the outdoors.

Dr. Michael Walczyk

Dr. Michael Walczyk

Dr. Michael Walczyk completed his Internal Medicine and Nephrology training at Oregon Health and Sciences University in Portland, Oregon. He served on the faculty of OHSU before joining N.W. Renal Clinic, a large single specialty nephrology practice with a comprehensive focus on nephrology, dialysis, transplantation, and critical care. He is now joining Hawaii Nephrologists in Hilo, HI.


He is originally from NYC and completed medical school in Philadelphia, PA.  Dr. Walczyk is married with two grown children. He and his wife Jacqueline share a passion for travel and enjoy recreation in the outdoors including hiking, biking, and camping.

Cecilia Green, DNP, APRN-Rx, NP-C

Cecilia Green, DNP, APRN-Rx, NP-C

Cecilia Green is a board-certified Nurse Practitioner. She completed her Doctor of Nursing Practice and Master of Science in Nursing degree at the University of Hawaii at Manoa. Her clinical practice focuses on health promotion and chronic disease management.


Born in the Philippines, Cecilia is fluent in English, Filipino and Ilonggo. She enjoys spending time with family and friends, reading and traveling. She also volunteers for the Hawaii Self-Advocacy Advisory Council (SAAC).

Kidney Care Education

We'd Like to See You


Clinics are available in Hilo, Kona and Waipahu. We are accepting new patients; please contact us to make an appointment.
All Insurances accepted.

Visit Us

Hawai'i Nephrologists
Hilo Office
75 Puuhonu Place, Suite #100
Hilo, HI 96720
Get Directions
 Phone: (808) 935-8647
 Fax: (808) 935-9783

Kailua Kona Office
75-184 Hualalai Rd.
Suite 202
Kailua Kona, HI 96740
Get Directions
 Phone: (808) 329-8251
 Fax: (808) 334-0130

Waipahu Office
94-229 Waipahu Depot Rd
Suite 101
Waipahu, HI 96797
Get Directions
 Phone: (808) 206-9849
 Fax: (808) 206-9850