Mark Fahlen, MD
NPI 1679539415 · Nephrology Physician · Modesto, CA
Enrolled with Medicare as Practitioner - Nephrology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Mark Fahlen, MD is a Nephrology Physician provider in Modesto, CA (NPI 1679539415).
Provider details
- NPI number
- 1679539415
- Entity type
- Individual
- Primary specialty
- Nephrology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- Yes
- License
- A81212 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
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
2,171 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) |
|---|---|---|
| Dialysis Services, 1 Physician Visit Per Month (20 Years Or Older)90962 | 772 | $209 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 487 | $123 |
| Hemodialysis Procedure With Physician Evaluation90935 | 362 | $72 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 334 | $80 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 76 | $118 |
| Dialysis Services, 2-3 Physician Visits Per Month (20 Years Or Older)90961 | 72 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 72 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Hydrocodone/Acetaminophenbrand: Hydrocodone-Acetaminophen | 471 | 64 |
| Parenteral Amino Acid 20% No.1brand: Prosol | 289 | — |
| Furosemide | 208 | 70 |
| Amlodipine Besylate | 144 | 49 |
| Calcium Acetate | 107 | 26 |
| Allopurinol | 105 | 33 |
| Gabapentin | 98 |
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-04-21
- Last updated
- 2011-08-02
Frequently asked questions
- What is Mark Fahlen's NPI number?
- Mark Fahlen's National Provider Identifier (NPI) is 1679539415, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Mark Fahlen's specialty?
- Mark Fahlen is listed in the NPPES registry with a primary specialty of Nephrology Physician (Allopathic & Osteopathic Physicians).
- Where is Mark Fahlen located?
- Mark Fahlen's practice location on file with NPPES is 1400 Florida Ave, Modesto, CA 95350-4422.
- What is Mark Fahlen's phone number?
- The practice phone number listed in the NPPES registry for Mark Fahlen is (209) 544-2910.
- Does Mark Fahlen accept Medicare?
- Mark Fahlen is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Mark Fahlen's NPI active?
- Yes — Mark Fahlen's NPI (1679539415) is active in the NPPES registry as of the last update on 2011-08-02.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.