Margarita Castro-Zarraga, M.D.
NPI 1578705679 · Family Medicine Physician · Lowell, MA
Enrolled with Medicare as Practitioner - Family Practice · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Margarita Castro-Zarraga, M.D. is a Family Medicine Physician provider in Lowell, MA (NPI 1578705679).
Provider details
- NPI number
- 1578705679
- Entity type
- Individual
- Primary specialty
- Family Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Female
- Sole proprietor
- No
- License
- 251722 (MA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
17 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)28% of score
32 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) |
|---|---|---|
| Hemoglobin A1c Level83036 | 32 | $10 |
Typical Medicare-allowed amounts for these services range $10–$10 (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 · 73 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 326 | 98 |
| Amlodipine Besylate | 203 | 70 |
| Albuterol Sulfatebrand: Albuterol Sulfate Hfa | 185 | 43 |
| Gabapentin | 179 | 44 |
| Lisinopril | 161 | 51 |
| Metformin Hcl | 135 | 45 |
| Omeprazole |
Practice location
Mailing address
Additional practice locations (1)
- 275 Nichols RdFitchburg, MA 01420-1919Phone: (978) 878-8300Fax: (978) 665-5922
Registry dates
- Enumerated
- 2009-04-03
- Last updated
- 2024-01-03
- Certified
- 2024-01-03
Frequently asked questions
- What is Margarita Castro-Zarraga's NPI number?
- Margarita Castro-Zarraga's National Provider Identifier (NPI) is 1578705679, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Margarita Castro-Zarraga's specialty?
- Margarita Castro-Zarraga is listed in the NPPES registry with a primary specialty of Family Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Margarita Castro-Zarraga located?
- Margarita Castro-Zarraga's practice location on file with NPPES is 161 Jackson St, Lowell, MA 01852-2103.
- What is Margarita Castro-Zarraga's phone number?
- The practice phone number listed in the NPPES registry for Margarita Castro-Zarraga is (978) 937-9700.
- Does Margarita Castro-Zarraga accept Medicare?
- Margarita Castro-Zarraga is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Margarita Castro-Zarraga's NPI active?
- Yes — Margarita Castro-Zarraga's NPI (1578705679) is active in the NPPES registry as of the last update on 2024-01-03.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.