Mark Shields, MD
NPI 1366411555 · Internal Medicine Physician · Laguna Hills, CA
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Mark Shields, MD is a Internal Medicine Physician provider in Laguna Hills, CA (NPI 1366411555).
Provider details
- NPI number
- 1366411555
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- G77342 (CA)
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
20 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
1,021 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) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 354 | $138 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 203 | $98 |
| Annual Wellness Visit, Includes a Personalized Prevention Plan of Service (pps), Subsequent VisitG0439 | 92 | $140 |
| Insertion of Needle Into Vein for Collection of Blood Sample36415 | 43 | $9 |
| Blood Test, Comprehensive Group of Blood Chemicals80053 | 40 | $10 |
| Administration of Influenza Virus VaccineG0008 | 36 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 118 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Atorvastatin Calcium | 453 | 132 |
| Losartan Potassium | 256 | 76 |
| Amlodipine Besylate | 251 | 73 |
| Levothyroxine Sodium | 242 | 73 |
| Pantoprazole Sodium | 217 | 72 |
| Rosuvastatin Calcium | 205 | 50 |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-03-17
- Last updated
- 2025-11-28
- Certified
- 2025-11-28
Frequently asked questions
- What is Mark Shields's NPI number?
- Mark Shields's National Provider Identifier (NPI) is 1366411555, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Mark Shields's specialty?
- Mark Shields is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Mark Shields located?
- Mark Shields's practice location on file with NPPES is 24221 Calle De La Louisa, Laguna Hills, CA 92653-7638.
- What is Mark Shields's phone number?
- The practice phone number listed in the NPPES registry for Mark Shields is (949) 588-8700.
- Does Mark Shields accept Medicare?
- Mark Shields is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Mark Shields's NPI active?
- Yes — Mark Shields's NPI (1366411555) is active in the NPPES registry as of the last update on 2025-11-28.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.