Mark A. Castellaw, MD
NPI 1114928793ActiveIndividual· Internal Medicine· Germantown, TN
Internal Medicine (MD) with Baptist Memorial Medical Group, Inc., practicing in Germantown, Tennessee. Their prescriptions cost Medicare Part D more than their services did: $1,044,784 for 12,790 claims, against $487,442 paid for services in 2024. Novo Nordisk Inc was the largest of 10 companies reporting payments in 2025, $429.06 in all, mostly food and beverage. Lists Baptist Memorial Hospital and 4 other hospitals as hospital affiliations.
Overview
| NPI | 1114928793 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD |
| Sole proprietor | No |
| NPI issued | Aug 9, 2005 |
| Last updated in NPPES | Oct 25, 2016 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine Primary | 207R00000X | 14060 | TN |
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 (TN) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 803 |
|---|---|
| Services billed | 21,414 across 139 procedure codes |
| Paid by Medicare | $487,442 |
Part D prescriptions in 2024
| Prescriptions (claims) | 12,790 · 28,754 30-day fills |
|---|---|
| Patients | 871 |
| Total drug cost | $1,044,784 |
| Generic share | 87% of claims |
Education and affiliations
| Graduation year | 1981 |
|---|---|
| Medicare specialty | Internal Medicine |
Medical group
- Baptist Memorial Medical Group, Inc.Germantown, TN · 576 clinicians
Hospital affiliations
- Baptist Memorial HospitalMemphis, TN
- Baptist Memorial Hospital DesotoSouthaven, MS
- Baptist Memorial Hospital TiptonCovington, TN
- Methodist Hospitals of MemphisMemphis, TN
- St Francis HospitalMemphis, TN
Other facilities
- Baptist Trinity Homecare & HospiceHome health agency · Cordova, TN
- Beacon Home HealthHome health agency · Memphis, TN
- Homechoice Health ServicesHome health agency · Memphis, TN
- Nhc Homecare SomervilleHome health agency · Arlington, TN
- Tennessee Quality Care - Home HealthHome health agency · Parsons, TN
Industry payments (Open Payments)
- 2025$429.06 · 23 payments from 10 companies
- 2024$551.36 · 28 payments from 9 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Novo Nordisk Inc | $122.22 | 6 |
| Amgen Inc. | $71.06 | 5 |
| Abbott Laboratories | $68.07 | 3 |
| Lilly USA, LLC | $31.52 | 2 |
| Pfizer Inc. | $31.46 | 2 |
What the 2025 payments were for
- Food and Beverage$429.06 · 23 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records
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All 79 internal medicine physicians in Germantown · All internal medicine physicians in Tennessee