Alexander Nathan Klonoff, M.D.
Internal Medicine Physician · Los Angeles, CA
Alexander Nathan Klonoff, M.D. is an internal medicine physician with a practice address in Los Angeles, California, and NPI 1538629936, issued on Mar 21, 2019. Check the license (California A177588, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Alexander Nathan Klonoff
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- A177588 CA
Self-reported in NPPES; status is on the state search - Practice location
- 1200 N State St, Los Angeles, CA 90089
- Phone
- (323) 409-7556
- Enumerated
- Mar 21, 2019
- Record last updated
- Apr 9, 2025
- Medicare enrollment
- Enrolled (PECOS I20221222001996); accepts Medicare assignment
- Medical or professional school
- University Of Southern California Keck School Of Medicine, 2019
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
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A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Alexander Nathan Klonoff in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A177588Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
99% fewer Medicare Part D claims than the average internal medicine physician in 2024
17 Medicare Part D claims, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D.
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.
Bills Medicare through one group practice
- Cedars-Sinai Medical Care FoundationWest Hollywood, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Alexander Nathan Klonoff among 17,696 internal medicine physician records in California
Alexander Nathan Klonoff, M.D. is one of 17,696 internal medicine physician records with a practice address in California. 79% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2019, is newer than 86% of them.
- NPI issued2019 · 86% of these records are older, 11% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated2019 · median 2004 among the 11,065 with a school on file
- Record last updated2025 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
1,423 internal medicine physician records list a practice address in Los Angeles
They are 1,423 of the 69,537 NPPES records with a practice address in Los Angeles, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Los Angeles → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
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- Sarita Mohanty, MDLos Angeles, CA 900891730286683
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- Hoa Phan, D.O.Los Angeles, CA 900891295919686
- Jesse Sammons, MDLos Angeles, CA 900891871753707
Common questions
What is Alexander Nathan Klonoff, M.D.'s NPI number?
Alexander Nathan Klonoff, M.D.'s National Provider Identifier (NPI) is 1538629936, issued on Mar 21, 2019. An NPI identifies a provider in billing; it is not a license.
Where is Alexander Nathan Klonoff, M.D. located?
The NPPES record lists a practice address at 1200 N State St, Los Angeles, CA, 90089. Phone: (323) 409-7556. Providers update this record themselves, so call before visiting.
How can I verify Alexander Nathan Klonoff, M.D.'s license?
NPPES lists California license number A177588, 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 Alexander Nathan Klonoff, M.D. prescribe under Medicare Part D?
In 2024, Alexander Nathan Klonoff, M.D. had 17 Medicare Part D claims; the average among internal medicine physician prescribers was 3,176. 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.