Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Ryan D Holzmacher, MD

Individual provider Nephrology Physician · NPI 1598700601

Ryan D Holzmacher, MD is an Internal Medicine in Greenfield, Wisconsin. Graduated from Southern Illinois University School of Medicine in 1999, 27 years ago. Practices with Oak Medical SC, a 123-clinician group and accepts Medicare assignment. Licensed in Wisconsin.

Years since qualifying
27
Trained at
Southern Illinois University School of Medicine
Licensed in
WI
In the registry since
2006
Specialties on file
3
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

See every abbreviation used in this directory →

Practice location Address checks out

5017 S 110th St
Greenfield, WI 53228-3131
Phone: (414) 301-3531
Show map & directions

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

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence 42642-020 (WI)
Nephrology Physician Taxonomy 207RN0300X · Licence 42642-020 (WI)
Pain Medicine Physician Taxonomy 208VP0000X · Licence 42642-020 (WI)

Record details

NPI number1598700601
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedJune 20, 2006
Last updated in NPPESSeptember 20, 2024
Certification dateSeptember 20, 2024
Mailing address19050 Blue Ridge Ct, Brookfield, WI 53045-5103

Medicare enrollment

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

Medicare specialtyINTERNAL MEDICINE
Also practisesNEPHROLOGY
Medical schoolSOUTHERN ILLINOIS UNIVERSITY SCHOOL OF MEDICINE
Graduated 1999 (27 years in practice)
Group practice Oak Medical Sc — 123 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations2 on file with Medicare