Jeffrey C. Mark, M.D.
NPI 1487603155ActiveIndividual· Internal Medicine, Gastroenterology· Turlock, CA
Internal Medicine, Gastroenterology (M.D.) in Turlock, California, trained at University of Illinois College of Med (Chi/Peor/Rock/Chm-Urb) (class of 1992). Their prescriptions cost Medicare Part D more than their services did: $169,302 for 540 claims, against $92,829 paid for services in 2024. Janssen Biotech, Inc. was the largest of 3 companies reporting payments in 2025, $298.53 in all, mostly food and beverage.
Overview
| NPI | 1487603155 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D. |
| Sole proprietor | No |
| NPI issued | May 9, 2006 |
| Last updated in NPPES | Jul 13, 2026 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Gastroenterology Primary | 207RG0100X | G83524 | CA |
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 - Gastroenterology (CA) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 240 |
|---|---|
| Services billed | 862 across 10 procedure codes |
| Paid by Medicare | $92,829 |
Part D prescriptions in 2024
| Prescriptions (claims) | 540 · 789 30-day fills |
|---|---|
| Patients | 168 |
| Total drug cost | $169,302 |
| Generic share | 76% of claims |
Education and affiliations
| Medical school | University of Illinois College of Med (Chi/Peor/Rock/Chm-Urb) |
|---|---|
| Graduation year | 1992 |
| Medicare specialty | Gastroenterology |
| Secondary specialties | Internal Medicine |
Hospital affiliation
- Emanuel Medical CenterTurlock, CA
Industry payments (Open Payments)
- 2025$298.53 · 9 payments from 3 companies
- 2024$347.63 · 12 payments from 5 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Janssen Biotech, Inc. | $216.75 | 5 |
| Abbvie Inc. | $55.44 | 3 |
| Madrigal Pharmaceuticals | $26.34 | 1 |
What the 2025 payments were for
- Food and Beverage$298.53 · 9 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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