Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.
NPIDirectory

Dr. Erin Jo Mercer Terpstra, MD, PHD

Individual provider Student in an Organized Health Care Education/Training Program · NPI 1366005662

Dr. Erin Jo Mercer Terpstra, MD, PHD practises Internal Medicine in Sioux Falls, South Dakota. Qualified in 2019, 7 years ago. Practices with Sanford Medical Center, a 842-clinician group and accepts Medicare assignment. Licensed in South Dakota.

Years since qualifying
7
Licensed in
SD
In the registry since
2019
Specialties on file
2
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.
PHD — Doctor of Philosophy
A research doctorate. In healthcare it usually sits alongside a clinical licence.

See every abbreviation used in this directory →

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Practice location Address checks out

Student / training record This NPI belongs to someone enrolled in a health care training programme. It carries no licence and no practice of its own, so no address or phone number is published for it.

Sioux Falls, SD

No coordinates on file. Search this address in Google Maps

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence 13919 (SD)
Student in an Organized Health Care Education/Training Program Taxonomy 390200000X

Record details

NPI number1366005662
Entity typeIndividual (Type 1)
GenderFemale
Credentials MD , PHD
Sole proprietorNo
NPI enumeratedApril 22, 2019
Last updated in NPPESDecember 20, 2022
Certification dateDecember 20, 2022

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyINTERNAL MEDICINE
Medical schoolOTHER
Graduated 2019 (7 years in practice)
Group practice Sanford Medical Center — 842 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations4 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Removal of skin lesions 1–10 times
Removal or shaving of skin growth 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients207
Services billed 1,011 a service is one billed item, such as a visit, a test or a procedure
Average patient age74

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $118 6 payments · a meal or drink at a meeting or visit, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician. Those with a page here are linked.

  • Sanford Usd Medical Center Hospital · Sioux Falls, SD · listed as Sanford Medical Center Pharmacy
  • Avera @ Home Home health agency · Sioux Falls, SD · listed as Avera at Home
  • Sanford Home Health Home health agency · Sioux Falls, SD
  • Avera McKennan Hospital & University Health Center Hospital · Sioux Falls, SD
  • Orange City Area Health System Hospital · Orange City, IA
  • Sanford Canton-Inwood Medical Center - Cah Hospital · Canton, SD
  • Sanford Worthington Medical Center Hospital · Worthington, MN
  • Aveanna Home Health Home health agency · Sioux Falls, SD

Colleagues at Sanford Medical Center

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 842 clinicians in the practice; 12 are shown here.

Other providers in Sioux Falls