Mary Ellen Chang, DO
NPI 1649891987 · Emergency Medicine Physician · San Antonio, TX
Enrolled with Medicare as Practitioner - Emergency Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Mary Ellen Chang, DO is a Emergency Medicine Physician provider in San Antonio, TX (NPI 1649891987).
Provider details
- NPI number
- 1649891987
- Entity type
- Individual
- Primary specialty
- Emergency Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- DO
- Sex
- Female
- Sole proprietor
- No
- License
- BP10070592 (TX)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Student, Health Care
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
6 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
471 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Emergency Department Visit With High Level of Medical Decision Making99285 | 179 | $170 |
| Routine Electrocardiogram (ecg) Using at Least 12 Leads With Interpretation and Report Only93010 | 156 | $8 |
| Critical Care, First 30-74 Minutes99291 | 68 | $206 |
| Emergency Department Visit With Moderate Level of Medical Decision Making99284 | 47 | $115 |
| Electrocardiogram (ecg) 1 to 3 Leads With Review By Physician Only93042 | 21 | $7 |
Typical Medicare-allowed amounts for these services range $7–$206 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 6 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Cefdinir | 20 | 19 |
| Amoxicillin/Potassium Clavbrand: Amoxicillin-Clavulanate Potass | 19 | 19 |
| Doxycycline Hyclate | 15 | 15 |
| Methocarbamol | 14 | 14 |
| Prednisone | 13 | 13 |
| Ondansetron Hcl | 11 | — |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means , never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Practice location
Mailing address
Registry dates
- Enumerated
- 2020-04-28
- Last updated
- 2022-07-08
- Certified
- 2022-07-08
Frequently asked questions
- What is Mary Ellen Chang's NPI number?
- Mary Ellen Chang's National Provider Identifier (NPI) is 1649891987, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Mary Ellen Chang's specialty?
- Mary Ellen Chang is listed in the NPPES registry with a primary specialty of Emergency Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Mary Ellen Chang located?
- Mary Ellen Chang's practice location on file with NPPES is 7703 Floyd Curl Dr # 7736, San Antonio, TX 78229-3901.
- What is Mary Ellen Chang's phone number?
- The practice phone number listed in the NPPES registry for Mary Ellen Chang is (210) 567-4621.
- Does Mary Ellen Chang accept Medicare?
- Mary Ellen Chang is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Mary Ellen Chang's NPI active?
- Yes — Mary Ellen Chang's NPI (1649891987) is active in the NPPES registry as of the last update on 2022-07-08.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.