Mark Francis Grenquist, DO
NPI 1942300454ActiveIndividual· Internal Medicine· Chelsea, MI
Internal Medicine (DO) in Chelsea, Michigan, trained at Michigan State University College of Human Medicine (class of 2001). 109 Medicare patients in 2024, $22,087 paid; nearly all of their 194 Part D prescriptions were generic (93%).
Overview
| NPI | 1942300454 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | DO |
| Sole proprietor | No |
| NPI issued | Sep 24, 2006 |
| Last updated in NPPES | Sep 6, 2016 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | 5101014936 | MI |
| Hospitalist | 208M00000X | 5101014936 | MI |
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 - Hospitalist (MI) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 109 |
|---|---|
| Services billed | 306 across 7 procedure codes |
| Paid by Medicare | $22,087 |
Part D prescriptions in 2024
| Prescriptions (claims) | 194 · 204 30-day fills |
|---|---|
| Patients | 104 |
| Total drug cost | $5,921 |
| Generic share | 93% of claims |
Education and affiliations
| Medical school | Michigan State University College of Human Medicine |
|---|---|
| Graduation year | 2001 |
| Medicare specialty | Hospitalist |
| Secondary specialties | Internal Medicine |
Medical group
- Apogee Medical Group Michigan PCMarshall, MI · 45 clinicians
Hospital affiliations
- Borgess Medical CenterKalamazoo, MI
- Oaklawn HospitalMarshall, MI
Industry payments (Open Payments)
None reported for 2025 or 2024.
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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