Nektarios S. Demetriou, DO earned a degree of a Doctor of Osteopathic Medicine. Licenses and Affiliations. Nektarios S. Demetriou, DO has been registered with the National Provider Identifier database since April 04, 2007, and his NPI number is 1154443521. Dr. Demetriou certified his NPI information on 03/05/2021. Book an Appointment.