Dr. William Hemsley Merwin III, MD
- Medicare services, 2022
- 567
- Part D claims, 2024
- 332
- Hospital affiliations
- 3
- Industry payments
- $232
- Medical groups
- 2
- Practice address
- 400 West Seventh St, Frederick, MD 21701
- Practice phone
- Call (240) 566-3300
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Find Dr. Merwin's professional email, personal email and mobile number
Dmand AI checks each channel through healthcare-specific waterfall enrichment. See what is on file with a free account, with practice phones, licenses and affiliations.
Dr. William Hemsley Merwin III is an internist in Frederick, Maryland
Dr. Merwin practices at Frederick Health Hospital in Frederick, Maryland, part of Frederick Health.
Dr. Merwin's NPI, 1043697600, was assigned on May 4, 2015. Dr. Merwin graduated from Georgetown University School of Medicine in 2015. Dr. Merwin holds Maryland license D0091613.
- NPI
- 1043697600NPI Registry (opens in a new tab)
- Medicare PAC ID
- 5799185633
- NPI enumeration date
- May 4, 2015
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (240) 566-3300
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 37
- Medical school graduation
- 2015
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. William Hemsley Merwin III practices at Frederick Health Hospital in Frederick, Maryland
Dr. Merwin's primary practice is Frederick Health Hospital, at 400 West Seventh St, Frederick, MD 21701 in Frederick County. The practice phone is (240) 566-3300.
- Frederick Health Hospital400 West Seventh St, Frederick, MD 21701 · Frederick CountyPhone(240) 566-3300
Source: Dmand AI Affiliation Data
Dr. William Hemsley Merwin III is affiliated with 3 sites of care and 2 medical groups
Dr. Merwin's primary practice is Frederick Health Hospital in Frederick, Maryland, part of Frederick Health. Dr. Merwin is also affiliated with MedStar Franklin Square Medical Center. The medical group on file is MedStar Medical Group. Dmand AI also links Dr. Merwin to 1 more hospital and 1 medical group, each named with a free account.
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dr. William Hemsley Merwin III's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Merwin practices, 3 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Frederick Health Hospital | Available with a free account |
| +2 more sites and 1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. William Hemsley Merwin III is one of 3,320 internists in Maryland
Internal medicine is Dr. Merwin's primary specialty in the NPI Registry, under taxonomy code 207R00000X. Dr. Merwin is licensed in Maryland.
Specialties and state licenses
- Internal medicine, MarylandPrimary
Internists near Dr. Merwin
Counts of internists with a Dmand AI profile, by place and practice. Each opens the list.
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; and Dmand AI Peer Benchmarks
Dr. William Hemsley Merwin III billed Medicare for 567 services in 2022
CMS data shows 567 Medicare services from Dr. Merwin across 8 procedure codes in 2022. Medicare paid $56,639 for them. Every service was in a facility, such as a hospital, rather than an office.
Dr. Merwin's Medicare services by type, 2021 to 2022
- 2021
- 2022
- Office and hospital visits
- 2021: 4372022: 56730%
Dr. Merwin compared with the Maryland median for internists, 2022
- Dr. Merwin
- Maryland median
- Medicare services
- 567vs 65614% below
- Part D claims
- 217vs 30930% below
Medians across 3,215 internists in Maryland with Dmand AI profiles that report each measure.
Dr. Merwin's most billed Medicare procedure codes, 2022
CMS publishes codes billed for 11 or more Medicare patients. Each label is the code family; CPT descriptions are licensed by the AMA.
Need commercial claims for Dr. Merwin?
Medicare shows one payer. Book a meeting to get commercial claims data for Dr. Merwin and other internists in Maryland.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. William Hemsley Merwin III's patients have a median age of 65
Across all payers, Dmand AI patient panel data puts Dr. Merwin's median patient age at 65, with 75% women.
Dr. Merwin's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 65
Patient panel by sex, all payers
- Women75%
- Men25%
Source: Dmand AI Patient Panel Data
Dr. William Hemsley Merwin III wrote 332 Medicare Part D claims in 2024
In 2024, Dr. Merwin wrote 332 Medicare Part D claims for 55 patients. 38% of them were for generic drugs. CMS names the drug for 217 of them, across 10 drugs with 11 or more claims each, at $49,505 in total drug cost. In 2023, CMS named 164 claims across 8 drugs.
Dr. Merwin's Part D claims by kind of drug, 2024
- Generic126 claims38%
- Brand-name206 claims62%
Dr. Merwin's most prescribed drugs by claims, 2024
CMS names a drug when it has 11 or more claims. Share is of the claims for drugs CMS names.
Drug classes CMS tracks in Dr. Merwin's Part D claims, 2024
- Antibiotics9%29 of 332 claims
Share of all Part D claims for each drug class CMS reports on. Classes with no claims are left out.
Part D claims for drugs CMS names, 2023 to 2024
- 2023
- 2024
- Claims for drugs CMS names
- 2023: 1642024: 21732%
Drugs named by CMS: 10 in 2024, 8 in 2023.
Sources: Medicare Part D Prescribers - by Provider and Drug (CMS), 2024 data, released May 6, 2026; and Medicare Part D Prescribers - by Provider (CMS), 2024 data
How Dr. William Hemsley Merwin III takes part in Medicare
Dr. Merwin accepts Medicare assignment, so Medicare's approved amount is taken as full payment.
- Accepts Medicare assignment
- Yes
Source: Doctors and Clinicians National Downloadable File (CMS)
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Dr. William Hemsley Merwin III received $232 in industry payments from 2017 to 2025
CMS Open Payments shows 2 general payments to Dr. Merwin from 2 drug and device companies from 2017 to 2025. Food and beverage make up the largest share, 100% of the total. Inspire Medical Systems, Inc. paid the most, $138.
General payments to Dr. Merwin by program year, 2017 to 2025
Companies that paid Dr. Merwin the most, 2017 to 2025
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. William Hemsley Merwin III graduated from Georgetown University School of Medicine
Dr. Merwin graduated from Georgetown University School of Medicine in 2015.
- Medical school
Source: Dmand AI Professional Profile Data
Sources for Dr. William Hemsley Merwin III's profile data
| Data on this page | Source |
|---|---|
| NPI, name, sex, specialty and licenses | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Professional Profile Data |
| Practice locations and phone | Dmand AI Affiliation Data |
| Primary practice, affiliations and health system | Dmand AI Affiliation DataDmand AI Org Hierarchy Data |
| Medicare services and procedure codes | Medicare Physician & Other Practitioners - by Provider and Service (CMS) (opens in a new tab) |
| State medians for the same specialty | Dmand AI Peer Benchmarks |
| Medicare patients and the all-payer patient panel | Dmand AI Patient Panel Data |
| Part D prescribing | Medicare Part D Prescribers - by Provider and Drug (CMS) (opens in a new tab)Medicare Part D Prescribers - by Provider (CMS) (opens in a new tab) |
| MIPS scores, telehealth, assignment and procedure percentiles | Doctors and Clinicians National Downloadable File (CMS) (opens in a new tab) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| EHR at each practice site | Dmand AI Technology Install Data |
| Similar physicians | Dmand AI Affiliation Data |
Data last refreshed October 2026Report an inaccuracyRemove my information
FAQ
Frequently asked questions about Dr. William Hemsley Merwin III
Spotted something out of date? Email hello@dmand.ai and we will check the record. Contact details live in the free trial.
What is Dr. William Hemsley Merwin III's NPI number?
Dr. William Hemsley Merwin III's NPI number is 1043697600. It was assigned on May 4, 2015, and it is active in the NPI Registry.
What kind of doctor is Dr. William Hemsley Merwin III?
Dr. William Hemsley Merwin III is an internist in Frederick, Maryland. The primary specialty in the NPI Registry is Internal Medicine Physician (taxonomy code 207R00000X).
Where does Dr. William Hemsley Merwin III practice?
Dr. Merwin practices at 400 West Seventh St, Frederick, MD 21701. Dr. Merwin's primary practice is Frederick Health Hospital in Frederick, Maryland, part of Frederick Health. Dmand AI also links Dr. Merwin to 1 hospital and 1 medical group.
What is Dr. William Hemsley Merwin III's office phone number?
The practice phone on file for Dr. Merwin is (240) 566-3300.
What is Dr. William Hemsley Merwin III's medical license number?
Dr. Merwin holds Maryland license D0091613.
Which hospitals is Dr. William Hemsley Merwin III affiliated with?
Dr. Merwin practices at Frederick Health Hospital in Frederick, Maryland. Dr. Merwin is also affiliated with MedStar Franklin Square Medical Center. Dmand AI links Dr. Merwin to 1 more hospital.
What medical group is Dr. William Hemsley Merwin III part of?
Dr. Merwin is linked to MedStar Medical Group. Dmand AI links Dr. Merwin to 1 more medical group.
Does Dr. William Hemsley Merwin III accept Medicare?
Yes. CMS data shows Dr. Merwin billed Medicare for 567 services in 2022, and Dr. Merwin accepts Medicare assignment.
What services does Dr. William Hemsley Merwin III bill to Medicare?
In 2022, Dr. Merwin's most billed Medicare services were hospital inpatient care (99233), hospital inpatient care (99223) and hospital inpatient care (99226).
Where did Dr. William Hemsley Merwin III go to medical school?
Dr. Merwin graduated from Georgetown University School of Medicine in 2015.
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What drugs does Dr. William Hemsley Merwin III prescribe most?
In 2024 Medicare Part D data, Dr. Merwin's most prescribed drugs by claims were Albuterol Sulfate Hfa, Trelegy Ellipta and Prednisone.
Has Dr. William Hemsley Merwin III received payments from drug or device companies?
CMS Open Payments shows $232 in general payments to Dr. Merwin from 2 companies from 2017 to 2025. The largest total came from Inspire Medical Systems, Inc.
How long has Dr. William Hemsley Merwin III been practicing?
Dr. Merwin graduated from medical school in 2015, 11 years ago.
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