John Constantine Gretes, MD
NPI 1043248453ActiveIndividual· Internal Medicine, Nephrology· Gloucester, VA
Internal Medicine, Nephrology (MD) in Gloucester, Virginia, trained at Duke University School of Medicine (class of 1972). Their prescriptions cost Medicare Part D more than their services did: $254,797 for 3,092 claims, against $127,049 paid for services in 2024. Ardelyx, Inc. reported $79.44 in payments in 2025, mostly food and beverage.
Overview
| NPI | 1043248453 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | Jun 28, 2006 |
| Last updated in NPPES | Mar 1, 2021 |
| Certified by provider | Mar 1, 2021 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Nephrology Primary | 207RN0300X | 0101025205 | VA |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Nov 10, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 11, 2026 | No match | — |
| New York OMIG · Nov 11, 2026 | No match | — |
| Ohio Medicaid · Nov 11, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 11, 2026 | No match | — |
| Washington HCA · Nov 11, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Nephrology (VA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 434 |
|---|---|
| Services billed | 1,234 across 26 procedure codes |
| Paid by Medicare | $127,049 |
Part D prescriptions in 2024
| Prescriptions (claims) | 3,092 · 6,817 30-day fills |
|---|---|
| Patients | 433 |
| Total drug cost | $254,797 |
| Generic share | 94% of claims |
Education and affiliations
| Medical school | Duke University School of Medicine |
|---|---|
| Graduation year | 1972 |
| Medicare specialty | Nephrology |
Medical group
- Riverside Physician Services IncWilliamsburg, VA · 797 clinicians
Hospital affiliations
- Rappahannock General HospitalKilmarnock, VA
- Riverside Doctors' Hospital of WilliamsburgWilliamsburg, VA
- Riverside Regional Medical CenterNewport News, VA
- Riverside Walter Reed HospitalGloucester, VA
Other facilities
- Rai Care Center GloucesterDialysis facility · Gloucester, VA
Industry payments (Open Payments)
- 2025$79.44 · 2 payments from 1 company
- 2024$153.88 · 10 payments from 5 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Ardelyx, Inc. | $79.44 | 2 |
What the 2025 payments were for
- Food and Beverage$79.44 · 2 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
Other nephrologists in Gloucester
- 1609843085
- 1669821856