Erin Jo Mercer Terpstra, MD, PHD
NPI 1366005662ActiveIndividual· Internal Medicine· Sioux Falls, SD
Internal Medicine (MD, PHD) with Sanford Medical Center, practicing in Sioux Falls, South Dakota. Their prescriptions cost Medicare Part D more than their services did: $285,297 for 4,427 claims, against $43,496 paid for services in 2024. Amgen Inc. was the largest of 4 companies reporting payments in 2025, $117.84 in all, mostly food and beverage. Lists Avera McKennan Hospital & University Health Center and 4 other hospitals as hospital affiliations.
Overview
| NPI | 1366005662 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD, PHD |
| Sole proprietor | No |
| NPI issued | Apr 22, 2019 |
| Last updated in NPPES | Dec 20, 2022 |
| Certified by provider | Dec 20, 2022 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | 13919 | SD |
| Student in an Organized Health Care Education/Training Program | 390200000X | — | — |
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 - Internal Medicine (SD) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 207 |
|---|---|
| Services billed | 1,011 across 22 procedure codes |
| Paid by Medicare | $43,496 |
Part D prescriptions in 2024
| Prescriptions (claims) | 4,427 · 8,791 30-day fills |
|---|---|
| Patients | 413 |
| Total drug cost | $285,297 |
| Generic share | 91% of claims |
Education and affiliations
| Graduation year | 2019 |
|---|---|
| Medicare specialty | Internal Medicine |
Medical group
- Sanford Medical CenterSioux Falls, SD · 857 clinicians
Hospital affiliations
- Avera McKennan Hospital & University Health CenterSioux Falls, SD
- Orange City Area Health SystemOrange City, IA
- Sanford Canton-Inwood Medical Center - CahCanton, SD
- Sanford Usd Medical CenterSioux Falls, SD
- Sanford Worthington Medical CenterWorthington, MN
Other facilities
- Aveanna Home HealthHome health agency · Sioux Falls, SD
- Avera @ HomeHome health agency · Sioux Falls, SD
- Sanford Home HealthHome health agency · Sioux Falls, SD
Industry payments (Open Payments)
- 2025$117.84 · 6 payments from 4 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Amgen Inc. | $69.29 | 3 |
| Dexcom, Inc. | $19.19 | 1 |
| Boehringer Ingelheim Pharmaceuticals, Inc. | $14.83 | 1 |
| Pfizer Inc. | $14.53 | 1 |
What the 2025 payments were for
- Food and Beverage$117.84 · 6 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All 124 internal medicine physicians in Sioux Falls · All internal medicine physicians in South Dakota