Mariana Chavez Mac Gregor, M.D., M.S.C.
NPI 1740408624ActiveIndividual· Internal Medicine· Houston, TX
Internal Medicine (M.D., M.S.C.) with Physicians Referral Service, practicing in Houston, Texas. Their prescriptions cost Medicare Part D more than their services did: $575,876 for 88 claims, against $15,623 paid for services in 2024. Pfizer Inc. was the largest of 4 companies reporting payments in 2025, $33,014 in all, mostly consulting fees.
Overview
| NPI | 1740408624 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | M.D., M.S.C. |
| Sole proprietor | No |
| NPI issued | Apr 23, 2007 |
| Last updated in NPPES | Jun 20, 2012 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | P2211 | TX |
| Internal Medicine | 207R00000X | 2005015456 | MO |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Oct 9, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 10, 2026 | No match | — |
| New York OMIG · Nov 10, 2026 | No match | — |
| Ohio Medicaid · Nov 10, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 10, 2026 | No match | — |
| Washington HCA · Nov 10, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Medical Oncology (TX) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 66 |
|---|---|
| Services billed | 160 across 8 procedure codes |
| Paid by Medicare | $15,623 |
Part D prescriptions in 2024
| Prescriptions (claims) | 88 · 123 30-day fills |
|---|---|
| Patients | 21 |
| Total drug cost | $575,876 |
| Generic share | 52% of claims |
Education and affiliations
| Graduation year | 2003 |
|---|---|
| Medicare specialty | Medical Oncology |
| Secondary specialties | Internal Medicine |
| Telehealth | Offers telehealth |
Medical group
- Physicians Referral ServiceHouston, TX · 2,765 clinicians
Industry payments (Open Payments)
- 2025$33,014 · 12 payments from 4 companies
- 2024$22,332 · 19 payments from 7 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Pfizer Inc. | $12,460 | 2 |
| Astrazeneca Pharmaceuticals LP | $9,324 | 5 |
| Genentech, Inc. | $7,988 | 3 |
| Astrazeneca Uk Limited | $3,243 | 2 |
What the 2025 payments were for
- Consulting Fee$31,603 · 10 payments
- Compensation for services other than consulting, including serving as faculty or as a speaker at a venue other than a continuing education program$1,335 · 1 payment
- Food and Beverage$76.00 · 1 payment
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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