Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Dr. John Frederick Shield, MD

Individual provider Internal Medicine Physician · NPI 1033189634

Dr. John Frederick Shield, MD practises Internal Medicine in Sonora, California. Qualified in 1980, 46 years ago. Practices with Union Associated Physicians Clinic, LLC, a 231-clinician group and accepts Medicare assignment. Licensed in California.

Years since qualifying
46
Licensed in
CA
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

690 Guzzi Ln Ste A
Sonora, CA 95370-5289
Phone: (209) 536-5070
Show map & directions

Directions in Google Maps · Apple Maps · OpenStreetMap

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence G45205 (CA)

Record details

NPI number1033189634
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedJanuary 25, 2006
Last updated in NPPESJune 24, 2024
Certification dateJune 24, 2024

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyINTERNAL MEDICINE
Medical schoolOTHER
Graduated 1980 (46 years in practice)
Group practice Union Associated Physicians Clinic, Llc — 231 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations4 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Melanoma (skin cancer) excision 1–10 times
Removal of skin lesions 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients910
Services billed 4,103 a service is one billed item, such as a visit, a test or a procedure
Average patient age76

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician. Those with a page here are linked.

  • Union Hospital Inc Hospital · Terre Haute, IN · listed as Union Hospital, Inc
  • Adventist Health Sonora Hospital · Sonora, CA

Colleagues at Union Associated Physicians Clinic, LLC

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 231 clinicians in the practice; 12 are shown here.

Other providers in Sonora