Mark J. Kasselik, MD
Nephrology Physician · San Francisco, CA
Mark J. Kasselik, MD is a nephrology physician with a practice address in San Francisco, California, and NPI 1891860193, issued on Nov 21, 2006. Check the license (California G62355, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Mark J. Kasselik
- Credential
- MD
- Primary taxonomy
- Nephrology Physician 207RN0300X
- License number
- G62355 CA
Self-reported in NPPES; status is on the state search - Practice location
- 2100 Webster Street, San Francisco, CA 94115
- Phone
- (415) 923-3456
- Enumerated
- Nov 21, 2006
- Record last updated
- Jul 18, 2013 (not updated in 13 years: call before relying on the address or phone)
- Fax
- (415) 923-3121
- Medicaid ID
- 00G623551 CA
- Entity
- Type 1 · individual
8 nearest nephrology physician records → All 1,468 in California → Look up another NPI →
Also registered at 2100 Webster Street
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Mark J. Kasselik in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G62355Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
96% fewer Medicare Part D claims than the average nephrology physician in 2024
62 Medicare Part D claims for 12 beneficiaries, against an average of 1,465 among the 10,986 providers of this specialty who prescribed in Part D. Brand-name drugs were 24% of 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.
Mark J. Kasselik among 1,468 nephrology physician records in California
Mark J. Kasselik, MD is one of 1,468 nephrology physician records with a practice address in California. 88% 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 10% of them.
- NPI issued2006 · 10% of these records are older, 48% newer
- In a Medicare fileYes · 88% of these records are
- In the CMS Doctors and Clinicians fileNo · 77% of these records are
- Record last updated2013 · 62% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RN0300X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Nephrology Physician providers in California
There are 1,468 nephrology physician records in California.
All 1,468 in California → Every provider in San Francisco → Nephrology Physician nationwide →
The 8 nephrology physician records with the nearest ZIP codes
- Jamshid Amanzadeh, MDSan Francisco, CA 941151629170428
- Joshua Bernstein, M.D.San Francisco, CA 941151457317729
- Michael Borah, MDSan Francisco, CA 941151144395435
- Alan Coleman, M.D.San Francisco, CA 941151013089580
- Tracy Jonelis, MDSan Francisco, CA 941151942372776
- Sepehr Keyhani, MDSan Francisco, CA 941151952713570
- Manjula Kurella, MD, MPHSan Francisco, CA 941151720032972
- Jonathan Lieberman, MDSan Francisco, CA 941151174601728
Common questions
What is Mark J. Kasselik, MD's NPI number?
Mark J. Kasselik, MD's National Provider Identifier (NPI) is 1891860193, issued on Nov 21, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Mark J. Kasselik, MD located?
The NPPES record lists a practice address at 2100 Webster Street, San Francisco, CA, 94115. Phone: (415) 923-3456. Providers update this record themselves, so call before visiting.
How can I verify Mark J. Kasselik, MD's license?
NPPES lists California license number G62355, 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 Mark J. Kasselik, MD prescribe under Medicare Part D?
In 2024, Mark J. Kasselik, MD had 62 Medicare Part D claims for 12 beneficiaries; the average among nephrology physician prescribers was 1,465. Part D covers Medicare prescriptions only.
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.