Marlon Decastro, M.D.
Internal Medicine Physician · Santa Rosa, CA
Marlon Decastro, M.D. is an internal medicine physician with a practice address in Santa Rosa, California, and NPI 1780643270, issued on Mar 22, 2006. Check the license (California C53594, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Marlon Decastro
- Credential
- M.D.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License numbers
- C53594 CA
23181 SC
Self-reported in NPPES; status is on the state search - Practice location
- 500 Doyle Park Dr, Santa Rosa, CA 95405
- Phone
- (707) 303-8300
- Enumerated
- Mar 22, 2006
- Record last updated
- Mar 7, 2023
- Fax
- (707) 303-8301
- Medicaid ID
- 231813 SC
- Medicare enrollment
- Enrolled (PECOS I20100316000335); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 500 Doyle Park Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Nicholas Anton, MDInternal Medicine Physician1659364933
- Razi Arifuddin, MDGastroenterology Physician1124085410
- Chad Barylski, NP-C, RN, DC, DACBSPNurse Practitioner1932358553
- Joshua Beirne, M.D.Gastroenterology Physician1841216041
- George Bisbee, MDInternal Medicine Physician1235122516
- Deborah Britt, M.D.Pediatrics Physician1316959307
Verify Marlon Decastro in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license C53594Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.7 times the Medicare Part D claims of the average internal medicine physician in 2024
8,435 Medicare Part D claims for 743 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 10% of claims. 244 claims were for opioids.
Most prescribed
- Atorvastatin Calcium680 claims
- Levothyroxine Sodium365 claims
- Amlodipine Besylate268 claims
- Lisinopril235 claims
- Losartan Potassium219 claims
- Metformin Hcl216 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.
Industry payments in 2024: $276.90
17 payments; by number, the most common kind was food and beverage; the largest payer was Pfizer Inc. The 50,334 providers of this specialty with any payment received $1,303.06 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- Providence Medical FoundationSanta Rosa, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Marlon Decastro among 17,696 internal medicine physician records in California
Marlon Decastro, 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 2006, is newer than 5% of them.
- NPI issued2006 · 5% of these records are older, 56% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1997 · median 2004 among the 11,065 with a school on file
- Record last updated2023 · 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).
98 internal medicine physician records list a practice address in Santa Rosa
They are 98 of the 6,884 NPPES records with a practice address in Santa Rosa, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Santa Rosa → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Nicholas Anton, MDSanta Rosa, CA 954051659364933
- George Bisbee, MDSanta Rosa, CA 954051235122516
- David Capaccio, DOSanta Rosa, CA 954051457355364
- David Charp, M.D.Santa Rosa, CA 954051053335208
- Catherine Davis, MDSanta Rosa, CA 954051497748776
- John Hurwitz, DOSanta Rosa, CA 954051124018262
- Adina Logan, M.D.Santa Rosa, CA 954051881667178
- Larry Marianella, M.D.Santa Rosa, CA 954051144257486
Common questions
What is Marlon Decastro, M.D.'s NPI number?
Marlon Decastro, M.D.'s National Provider Identifier (NPI) is 1780643270, issued on Mar 22, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Marlon Decastro, M.D. located?
The NPPES record lists a practice address at 500 Doyle Park Dr, Santa Rosa, CA, 95405. Phone: (707) 303-8300. Providers update this record themselves, so call before visiting.
How can I verify Marlon Decastro, M.D.'s license?
NPPES lists California license number C53594, 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 Marlon Decastro, M.D. prescribe under Medicare Part D?
In 2024, Marlon Decastro, M.D. had 8,435 Medicare Part D claims for 743 beneficiaries; 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.