Mark Day, DO
Family Medicine Physician · Las Vegas, NV
Mark Day, DO is a family medicine physician with a practice address in Las Vegas, Nevada, and NPI 1164436994, issued on Jul 28, 2006. Check the license (Nevada 656, as entered in NPPES) on the Nevada State Board of Medical Examiners; the Medicare figures below come from public CMS files.
- Name
- Mark Day
- Credential
- DO
- Primary taxonomy
- Family Medicine Physician 207Q00000X
- License number
- 656 NV
Self-reported in NPPES; status is on the state search - Practice location
- 1655 E Cactus Ave Ste 400, Las Vegas, NV 89183
- Phone
- (702) 724-8777
- Enumerated
- Jul 28, 2006
- Record last updated
- Nov 6, 2025
- Fax
- (702) 724-8749
- Medicare enrollment
- Enrolled (PECOS I20100924000328); accepts Medicare assignment
- Medical or professional school
- Des Moines University Of Osteopathic Medicine And Health Sciences, 1990
- Entity
- Type 1 · individual
8 nearest family medicine physician records → All 1,243 in Nevada → Look up another NPI →
Also registered at 1655 E Cactus Ave Ste 400
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Paige CejkaPhysician Assistant1205586104
- Erum Karafa, PA-CPhysician Assistant1437645736
- Joobin Park, M.D.Internal Medicine Physician1588028807
Verify Mark Day in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersNevada State Board of Medical Examiners
Search for license 656Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.2 times the Medicare Part D claims of the average family medicine physician in 2024
7,875 Medicare Part D claims for 763 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. Brand-name drugs were 10% of claims. 15 claims were for opioids.
Most prescribed
- Atorvastatin Calcium838 claims
- Amlodipine Besylate432 claims
- Levothyroxine Sodium397 claims
- Lisinopril340 claims
- Rosuvastatin Calcium314 claims
- Metformin Hcl301 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: $123.54
1 payment: food and beverage; the largest payer was Abbvie Inc. The 55,478 providers of this specialty with any payment received $902.55 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
- Optum Medical Group II Rhodes P CHenderson, NV
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mark Day among 1,243 family medicine physician records in Nevada
Mark Day, DO is one of 1,243 family medicine physician records with a practice address in Nevada. 77% 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 8% of them.
- NPI issued2006 · 8% of these records are older, 59% newer
- In a Medicare fileYes · 77% of these records are
- In the CMS Doctors and Clinicians fileYes · 58% of these records are
- Graduated1990 · median 2008 among the 726 with a school on file
- Record last updated2025 · 45% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a Nevada practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
578 family medicine physician records list a practice address in Las Vegas
They are 578 of the 65,269 NPPES records with a practice address in Las Vegas, and 1,243 family medicine physician records in Nevada.
All 1,243 in Nevada → Every provider in Las Vegas → Family Medicine Physician nationwide →
The 8 family medicine physician records with the nearest ZIP codes
- Aaron Adaoag, MDLas Vegas, NV 891831609834852
- James Joslin, D.O.Las Vegas, NV 891831164713400
- Govind Koka, DOLas Vegas, NV 891831942322466
- Ashley Mangahas Abad, MDLas Vegas, NV 891781306535455
- Chi Pham, MDLas Vegas, NV 891781952888935
- Wilbert Cain, M.D.Las Vegas, NV 891911134111610
- Paul Crawford, M.D.Nellis Afb, NV 891911578557278
- Michael Gauron, MDNellis Afb, NV 891911992799514
Common questions
What is Mark Day, DO's NPI number?
Mark Day, DO's National Provider Identifier (NPI) is 1164436994, issued on Jul 28, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Mark Day, DO located?
The NPPES record lists a practice address at 1655 E Cactus Ave Ste 400, Las Vegas, NV, 89183. Phone: (702) 724-8777. Providers update this record themselves, so call before visiting.
How can I verify Mark Day, DO's license?
NPPES lists Nevada license number 656, as entered by the provider. Search the Nevada State Board of Medical Examiners at https://medboard.nv.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mark Day, DO prescribe under Medicare Part D?
In 2024, Mark Day, DO had 7,875 Medicare Part D claims for 763 beneficiaries; the average among family medicine physician prescribers was 3,544. 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.