Dr. Gary Thomas Underhill, MD
- Medicare services, 2024
- 332
- Medicare patients, 2024
- 211
- Part D claims, 2024
- 208
- Hospital affiliations
- 2
- Medical groups
- 3
- Practice address
- 1012 South 3rd Street, Dayton, WA 99328
- Practice phone
- Call (509) 382-2531
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
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Dr. Gary Thomas Underhill is a family medicine physician in Dayton, Washington
Dr. Underhill practices at Dayton General Hospital in Dayton, Washington, part of Columbia County Health System.
Dr. Underhill's NPI, 1851375265, was assigned on November 30, 2005. Dr. Underhill graduated from Loma Linda University School of Medicine in 1996. Dr. Underhill holds Washington license MD00037711.
- NPI
- 1851375265NPI Registry (opens in a new tab)
- Medicare PAC ID
- 1850483470
- NPI enumeration date
- November 30, 2005
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Practice phone
- (509) 382-2531
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 56
- Medical school graduation
- 1996
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. Gary Thomas Underhill practices at Dayton General Hospital in Dayton, Washington
Dr. Underhill's primary practice is Dayton General Hospital, at 1012 South 3rd Street, Dayton, WA 99328 in Columbia County. The practice phone is (509) 382-2531.
- Dayton General Hospital1012 South 3rd Street, Dayton, WA 99328 · Columbia CountyPhone(509) 382-2531
Source: Dmand AI Affiliation Data
Dr. Gary Thomas Underhill is affiliated with 2 sites of care and 3 medical groups
Dr. Underhill's primary practice is Dayton General Hospital in Dayton, Washington, part of Columbia County Health System. Dr. Underhill is also affiliated with Trios Southridge Hospital. The medical group on file is Columbia County Health System. Dmand AI also links Dr. Underhill to 2 more medical groups, each named with a free account. Dr. Underhill's employer is on file too: a hospital.
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dr. Gary Thomas Underhill's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Underhill practices, 2 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Dayton General Hospital | Available with a free account |
| +1 more site and 2 medical groups | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Gary Thomas Underhill is one of 4,178 family medicine physicians in Washington
Family medicine is Dr. Underhill's primary specialty in the NPI Registry, under taxonomy code 207Q00000X. Dr. Underhill is licensed in Washington.
Specialties and state licenses
- Family medicine, WashingtonPrimary
Family medicine physicians near Dr. Underhill
Counts of family medicine physicians 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. Gary Thomas Underhill billed Medicare for 332 services in 2024
CMS data shows 332 Medicare services from Dr. Underhill across 6 procedure codes in 2024, for 211 Medicare patients. Medicare paid $26,350 for them. Every service was in a facility, such as a hospital, rather than an office.
Dr. Underhill's Medicare services by type, 2023 to 2024
- 2023
- 2024
- Office and hospital visits
- 2023: 2652024: 22415%
- Tests and treatments
- 2023: 1212024: 10811%
Dr. Underhill compared with the Washington median for family medicine physicians, 2024
- Dr. Underhill
- Washington median
- Medicare services
- 332vs 20066% above
- Medicare patients
- 211vs 1042.0 times
- Part D claims
- 46vs 60292% below
Medians across 4,334 family medicine physicians in Washington with Dmand AI profiles that report each measure.
Dr. Underhill's most billed Medicare procedure codes, 2024
CMS publishes codes billed for 11 or more Medicare patients. Each label is the code family; CPT descriptions are licensed by the AMA.
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Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. Gary Thomas Underhill treated 211 Medicare patients in 2024, average age 79
CMS counts 211 Medicare patients who saw Dr. Underhill in 2024. The largest group is 75 to 84, with 86 patients. 75% of them have high blood pressure, and 75% have high cholesterol. 20% are also on Medicaid. Their average risk score is 2.03, where 1.00 is the Medicare average, so they are sicker than most Medicare patients.
Across all payers, Dmand AI patient panel data puts Dr. Underhill's median patient age at 51, with 53% women.
Dr. Underhill's Medicare patients by age, 2024
Dr. Underhill's Medicare patients by sex, 2024
- Women12861%
- Men8339%
Chronic conditions among Dr. Underhill's Medicare patients, 2024
- High blood pressure75%
- High cholesterol75%
- Arthritis50%
- Diabetes43%
- Mood disorders41%
- Chronic kidney disease40%
- Depression39%
- Anxiety38%
Share of Medicare patients with each condition. A patient can have several.
Dr. Underhill's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 51
Patient panel by sex, all payers
- Women53%
- Men46%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. Gary Thomas Underhill wrote 208 Medicare Part D claims in 2024
In 2024, Dr. Underhill wrote 208 Medicare Part D claims for 116 patients. 94% of them were for generic drugs. CMS names the drug for 46 of them, across 3 drugs with 11 or more claims each, at $322 in total drug cost. In 2023, CMS named 54 claims across 3 drugs.
Dr. Underhill's Part D claims by kind of drug, 2024
- Generic195 claims94%
- Brand-name13 claims6%
Dr. Underhill'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. Underhill's Part D claims, 2024
- Opioids7%15 of 208 claims
- Antibiotics28%58 of 208 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: 542024: 4615%
Drugs named by CMS: 3 in 2024, 3 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. Gary Thomas Underhill takes part in Medicare
Dr. Underhill 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. Gary Thomas Underhill graduated from Loma Linda University School of Medicine
Dr. Underhill graduated from Loma Linda University School of Medicine in 1996.
- Medical school
Source: Dmand AI Professional Profile Data
Sources for Dr. Gary Thomas Underhill'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 DataMedicare Physician & Other Practitioners - by Provider (CMS) (opens in a new tab) |
| 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) |
| 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. Gary Thomas Underhill
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. Gary Thomas Underhill's NPI number?
Dr. Gary Thomas Underhill's NPI number is 1851375265. It was assigned on November 30, 2005, and it is active in the NPI Registry.
What kind of doctor is Dr. Gary Thomas Underhill?
Dr. Gary Thomas Underhill is a family medicine physician in Dayton, Washington. The primary specialty in the NPI Registry is Family Medicine Physician (taxonomy code 207Q00000X).
Where does Dr. Gary Thomas Underhill practice?
Dr. Underhill practices at 1012 South 3rd Street, Dayton, WA 99328. Dr. Underhill's primary practice is Dayton General Hospital in Dayton, Washington, part of Columbia County Health System. Dmand AI also links Dr. Underhill to 2 medical groups.
What is Dr. Gary Thomas Underhill's office phone number?
The practice phone on file for Dr. Underhill is (509) 382-2531.
What is Dr. Gary Thomas Underhill's medical license number?
Dr. Underhill holds Washington license MD00037711.
Which hospitals is Dr. Gary Thomas Underhill affiliated with?
Dr. Underhill practices at Dayton General Hospital in Dayton, Washington. Dr. Underhill is also affiliated with Trios Southridge Hospital.
What medical group is Dr. Gary Thomas Underhill part of?
Dr. Underhill is linked to Columbia County Health System. Dmand AI links Dr. Underhill to 2 more medical groups.
Does Dr. Gary Thomas Underhill accept Medicare?
Yes. CMS data shows Dr. Underhill billed Medicare for 332 services in 2024, and Dr. Underhill accepts Medicare assignment.
How many Medicare patients does Dr. Gary Thomas Underhill see?
CMS counts 211 Medicare patients who saw Dr. Underhill in 2024, with an average age of 79.
What services does Dr. Gary Thomas Underhill bill to Medicare?
In 2024, Dr. Underhill's most billed Medicare services were emergency department visit (99285), heart test or procedure (93010) and emergency department visit (99284).
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Where did Dr. Gary Thomas Underhill go to medical school?
Dr. Underhill graduated from Loma Linda University School of Medicine in 1996.
What drugs does Dr. Gary Thomas Underhill prescribe most?
In 2024 Medicare Part D data, Dr. Underhill's most prescribed drugs by claims were Prednisone, Cephalexin and Amoxicillin-Clavulanate Potass.
How long has Dr. Gary Thomas Underhill been practicing?
Dr. Underhill graduated from medical school in 1996, 30 years ago.
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