Dirk R. Diefendorf, MD

Medicare activity in 2024

Official CMS public-use data for Dirk R. Diefendorf, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.

Most frequent services

1. Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)274 services
2. Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)89 services
3. New patient office or other outpatient visit with moderate level of medical decision making, if using time, 45 minutes or more (99204)83 services
4. New patient office or other outpatient visit with low level of medical decision making, if using time, 30 minutes or more (99203)17 services
5. New patient office or other outpatient visit with a high level of medical decision making, if using time, 60 minutes or more (99205)11 services

Chronic conditions among these patients

Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).

• High cholesterol68%
• High blood pressure59%
• Arthritis55%
• Osteoporosis20%
• Ischemic heart disease18%
• Anxiety17%

Hospitals where Dirk R. Diefendorf works

Medicare's Facility Affiliation Data lists Dirk R. Diefendorf at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.

• Peninsula Medical CenterBurlingame, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050007

Practice locations

Addresses where Dirk R. Diefendorf is enrolled with Medicare (CMS data updated October 2, 2026).

• 101 S San Mateo Dr, Suite 212San Mateo, CA 94401 (650) 347‑0517

Specialties

• Orthopedic Surgeryprimary

Find other Orthopedic Surgery doctors in California →

Other orthopedic surgeons in San Mateo

Clinicians with the same Medicare primary specialty in San Mateo, CA — not a recommendation.

• Edward C. Sun, MD
• Noman Q. Khan, MD
• Jacqueline K. Nguyen, MD
• Marvin Y. Lo, MD
• Akira Yamamoto, MD
• Musa Zaid, MD
• James M. Hartford, MD
• Kris Okumu, MD

All orthopedic surgeons in San Mateo →

Clinician information

Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.

Sources

1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
6. Medicare Care Compare — official Medicare tool to look up clinicians