John Frederick Shield, MD
Internal Medicine Physician · Sonora, CA
John Frederick Shield, MD is an internal medicine physician with a practice address in Sonora, California, and NPI 1033189634, issued on Jan 25, 2006. Check the license (California G45205, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- John Frederick Shield
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- G45205 CA
Self-reported in NPPES; status is on the state search - Practice location
- 690 Guzzi LN, Sonora, CA 95370
- Phone
- (209) 536-5070
- Enumerated
- Jan 25, 2006
- Record last updated
- Jun 24, 2024
- Medicare enrollment
- Enrolled (PECOS I20250915000386); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 690 Guzzi LN
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Nickolas Dobler, PAPhysician Assistant1588641351
- Claire Mills, FNPWomen's Health Nurse Practitioner1720172455
- Daniel Phillips, M.D.Internal Medicine Physician1720042732
- Jacey Rodriguez-Serva, F.N.P.Family Nurse Practitioner1215255062
- Carolee Ross, N.P.Adult Health Nurse Practitioner1871698241
Verify John Frederick Shield in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G45205Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.9 times the Medicare Part D claims of the average internal medicine physician in 2024
9,360 Medicare Part D claims for 575 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 13% of claims. 82 claims were for opioids.
Most prescribed
- Amlodipine Besylate583 claims
- Losartan Potassium456 claims
- Valsartan455 claims
- Atorvastatin Calcium436 claims
- Levothyroxine Sodium355 claims
- Omeprazole321 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
The practice group's MIPS final score for 2023 (Medicare payment program): 79.2 of 100
The Merit-based Incentive Payment System score is reported for the practice group, not for one clinician alone. Four categories are weighted into the final score; the average among 454,083 clinicians with a measured score was 83.5.
Source: CMS Quality Payment Program, MIPS performance year 2023, group reporting; category weights for 2023 (qpp.cms.gov).
Bills Medicare through 3 group practices
- Sonora Community HospitalGroveland, CA
- Union Associated Physicians Clinic, LLCTerre Haute, IN
- Valley Professionals Community Health Center IncTerre Haute, IN
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
John Frederick Shield among 17,696 internal medicine physician records in California
John Frederick Shield, MD is one of 17,696 internal medicine physician records with a practice address in California. 79% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 5% of them.
- NPI issued2006 · 5% of these records are older, 56% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1980 · median 2004 among the 11,065 with a school on file
- Record last updated2024 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
17 internal medicine physician records list a practice address in Sonora
They are 17 of the 629 NPPES records with a practice address in Sonora, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Sonora → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- David Allen, M.D.Sonora, CA 953701184687535
- Leslie Brocchini, MDSonora, CA 953701811966047
- Brenda Forrest, M.DSonora, CA 953701538375365
- Jason Jeffery, M.D.Sonora, CA 953701427293836
- Daniel Meador, MDSonora, CA 953701619925989
- James Mosson, M.D.Sonora, CA 953701437135670
- Daniel Phillips, M.D.Sonora, CA 953701720042732
- Maureen Regan, MDSonora, CA 953701477532273
Common questions
What is John Frederick Shield, MD's NPI number?
John Frederick Shield, MD's National Provider Identifier (NPI) is 1033189634, issued on Jan 25, 2006. An NPI identifies a provider in billing; it is not a license.
Where is John Frederick Shield, MD located?
The NPPES record lists a practice address at 690 Guzzi LN, Sonora, CA, 95370. Phone: (209) 536-5070. Providers update this record themselves, so call before visiting.
How can I verify John Frederick Shield, MD's license?
NPPES lists California license number G45205, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does John Frederick Shield, MD prescribe under Medicare Part D?
In 2024, John Frederick Shield, MD had 9,360 Medicare Part D claims for 575 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
What is John Frederick Shield, MD's MIPS final score?
The 2023 MIPS final score is 79.2 of 100, reported for the practice group. The average among 454,083 clinicians with a measured score was 83.5.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.