Am J Physiol Renal Physiol
Diabetic NephropathiesEnzyme InhibitorsFeedback, Physiological
Dr. John Stephen Hammes, MD
NPI1891766994PAC ID7012166432
- Medicare services, 2024
- 2,257
- Medicare patients, 2024
- 432
- Part D claims, 2024
- 1,631
- Publications
- 5
- Hospital affiliations
- 3
- Practice address
- 720 Gateway Center Drive, Suite B, San Diego, CA 92102
- Practice phone
- Call (619) 264-4100
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Fresenius Kidney Care Gateway East
Dialysis Center - Independent · San Diego, California
Find Dr. Hammes' 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. John Stephen Hammes is a nephrologist in San Diego, California
Dr. Hammes practices at Fresenius Kidney Care Gateway East in San Diego, California.
Dr. Hammes' NPI, 1891766994, was assigned on January 28, 2006. Dr. Hammes graduated from Uniformed Services University, F. Edward Hebert School of Medicine in 1993. Dr. Hammes' California license number on file is G84351.
NPI and contact details
- NPI
- 1891766994NPI Registry (opens in a new tab)
- Medicare PAC ID
- 7012166432
- NPI enumeration date
- January 28, 2006
- NPI status
- Active
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
- Practice phone
- (619) 264-4100
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Male
- Estimated age
- 59
- Medical school graduation
- 1993
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. John Stephen Hammes practices at Fresenius Kidney Care Gateway East in San Diego, California
Dr. Hammes' primary practice is Fresenius Kidney Care Gateway East, at 720 Gateway Center Drive, Suite B, San Diego, CA 92102 in San Diego County. The practice phone is (619) 264-4100.
- Fresenius Kidney Care Gateway East720 Gateway Center Drive, Suite B, San Diego, CA 92102 · San Diego CountyPhone(619) 264-4100
Source: Dmand AI Affiliation Data
Dr. John Stephen Hammes is affiliated with 9 sites of care and 4 medical groups
Dr. Hammes' primary practice is Fresenius Kidney Care Gateway East in San Diego, California. Dr. Hammes is also affiliated with Scripps Mercy Hospital San Diego. The medical group on file is UC San Diego Health. Dmand AI also links Dr. Hammes to 2 more hospitals, 3 group practices and clinics, 3 medical groups and 2 dialysis centers, each named with a free account.
Fresenius Kidney Care Gateway EastPrimary
Sources: Dmand AI Affiliation Data; and Dmand AI Org Hierarchy Data
Dmand AI tracks the EHR system at Dr. John Stephen Hammes' practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Hammes practices, 9 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Fresenius Kidney Care Gateway East | Available with a free account |
| +8 more sites and 3 medical groups | Available with a free account |
Source: Dmand AI Technology Install Data
For health IT teams
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Dr. John Stephen Hammes is one of 1,401 nephrologists in California
Nephrology is Dr. Hammes' primary specialty in the NPI Registry, under taxonomy code 207RN0300X. Dr. Hammes is board certified in internal medicine by the American Board of Internal Medicine. Dr. Hammes has a license on file in California.
Specialties and state licenses
- Nephrology, CaliforniaPrimary
Clinical focus
Dmand AI lists acute kidney failure, chronic kidney disease, fluid and electrolyte imbalances and kidney disease among the conditions Dr. Hammes treats.
Nephrologists near Dr. Hammes
Counts of nephrologists 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. John Stephen Hammes billed Medicare for 2,257 services in 2024
CMS data shows 2,257 Medicare services from Dr. Hammes across 12 procedure codes in 2024, for 432 Medicare patients. Medicare paid $232,404 for them.
Medicare services, 20242,257
Medicare patients432
Paid by Medicare$232,404
Procedure codes12
Dr. Hammes' Medicare services by type, 2023 to 2024
- 2023
- 2024
- Office and hospital visits
- 2023: 1,2792024: 1,279No change
- Tests and treatments
- 2023: 7462024: 7551%
- Other services
- 2023: 02024: 223
Where Dr. Hammes' Medicare services took place, 2024
- In an office90040%
- In a facility1,35760%
Dr. Hammes compared with the California median for nephrologists, 2024
- Dr. Hammes
- California median
- Medicare services
- 2,257vs 1,0842.1 times
- Medicare patients
- 432vs 30741% above
- Part D claims
- 1,206vs 95526% above
Medians across 1,355 nephrologists in California with Dmand AI profiles that report each measure.
Dr. Hammes' 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.
Need commercial claims for Dr. Hammes?
Medicare shows one payer. Book a meeting to get commercial claims data for Dr. Hammes and other nephrologists in California.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. John Stephen Hammes treated 432 Medicare patients in 2024, average age 72
CMS counts 432 Medicare patients who saw Dr. Hammes in 2024. The largest group is 65 to 74, with 151 patients. 75% of them have chronic kidney disease, and 75% have high blood pressure. 57% are also on Medicaid. Their average risk score is 5.87, 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. Hammes' median patient age at 70, with 46% women.
Medicare patients, 2024432
Average age72
Average risk score5.87
Also on Medicaid57%
Dr. Hammes' Medicare patients by age, 2024
Dr. Hammes' Medicare patients by sex, 2024
- Women18844%
- Men24456%
Chronic conditions among Dr. Hammes' Medicare patients, 2024
- Chronic kidney disease75%
- High blood pressure75%
- High cholesterol75%
- Diabetes67%
- Heart failure63%
- Ischemic heart disease56%
- Arthritis46%
- Atrial fibrillation41%
Share of Medicare patients with each condition. A patient can have several.
Dr. Hammes' patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 70
Patient panel by sex, all payers
- Women46%
- Men53%
Sources: Dmand AI Patient Panel Data; and Medicare Physician & Other Practitioners - by Provider (CMS), 2024 data
Dr. John Stephen Hammes wrote 1,631 Medicare Part D claims in 2024
In 2024, Dr. Hammes wrote 1,631 Medicare Part D claims for 233 patients. 80% of them were for generic drugs. CMS names the drug for 1,206 of them, across 34 drugs with 11 or more claims each, at $324,577 in total drug cost. In 2023, CMS named 1,159 claims across 38 drugs.
Part D claims, 20241,631
Drugs named by CMS34
Total drug cost$324,577
Part D patients233
Dr. Hammes' Part D claims by kind of drug, 2024
- Generic1,301 claims80%
- Brand-name299 claims18%
- Other31 claims2%
Dr. Hammes' 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. Hammes' Part D claims, 2024
- Antibiotics1%18 of 1,631 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: 1,1592024: 1,2064%
Drugs named by CMS: 34 in 2024, 38 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
Dr. John Stephen Hammes offers telehealth to Medicare patients
Dr. Hammes accepts Medicare assignment, so Medicare's approved amount is taken as full payment. CMS lists Dr. Hammes as offering telehealth.
- Accepts Medicare assignment
- Yes
- Offers telehealth
- Yes
Source: Doctors and Clinicians National Downloadable File (CMS)
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Dr. John Stephen Hammes has 5 publications on record
Dmand AI links 5 papers to Dr. Hammes in 2004. The most frequent topics are Glomerular Filtration Rate, Rats, Wistar and Diabetic Nephropathies. Dr. Hammes' most frequent co-authors are Scott C. Thomson, MD, Francis B. Gabbai, MD and John T. Bestoso, MD.
Papers5
Topics Dr. Hammes writes about most
- Glomerular Filtration Rate
- Rats, Wistar
- Diabetic Nephropathies
- Feedback, Physiological
- Kidney Glomerulus
- Nitric Oxide Synthase
- Renal Circulation
Dr. Hammes' most frequent co-authors
- Scott C. Thomson, MD3 shared papers
- Francis B. Gabbai, MD2 shared papers
- John T. Bestoso, MD1 shared paper
Recent publications by Dr. Hammes
Am J Physiol Regul Integr Comp Physiol
Diabetes Mellitus, ExperimentalDiabetic NephropathiesDietary Proteins
AngiotensinsBenzolamideCarbonic Anhydrase Inhibitors
Squamous cell carcinoma in situ arising at the exit site of a tunneled catheter (opens in a new tab)
Am J Kidney Dis
Anus NeoplasmsBowen's DiseaseCarcinoma, Squamous Cell
Hospitals, MilitaryMeningitisMeningitis, Aseptic
See who Dr. Hammes researches with
Physician Network Discovery turns co-authorship, shared hospitals and shared groups into a map of who Dr. Hammes works with, so you can find a warm path to the right nephrologists.
Sources: PubMed (National Library of Medicine); and Dmand AI Research Linkage
Dr. John Stephen Hammes received $309 in industry payments from 2016 to 2024
CMS Open Payments shows 15 general payments to Dr. Hammes from 8 drug and device companies from 2016 to 2024. Food and beverage make up the largest share, 98% of the total. OPKO Pharmaceuticals, LLC paid the most, $68.
General payments to Dr. Hammes by program year, 2016 to 2024
General payments to Dr. Hammes by kind, 2016 to 2024
$309in total
- Food and beverage$30398%
- Education$52%
Companies that paid Dr. Hammes the most, 2016 to 2024
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Dr. John Stephen Hammes graduated from Uniformed Services University, F. Edward Hebert School of Medicine
Dr. Hammes graduated from Uniformed Services University, F. Edward Hebert School of Medicine in 1993.
- Medical school
- Board certified in internal medicine
- Board certified in nephrology
Source: Dmand AI Professional Profile Data
Dr. John Stephen Hammes accepts plans from 13 insurance carriers
Dr. Hammes is in network with 13 carriers, including Aetna, Blue Cross Blue Shield of Michigan and United Healthcare. Medicare plans come from the most carriers, 8. Check the plan with the practice before a visit.
- Aetna
- Blue Cross Blue Shield of Michigan
- United Healthcare
- Elevance
- Humana
- Blue Cross Blue Shield of Massachusetts
- HCSC
- Molina
- +5 more carriersWith a free account
Plan types Dr. Hammes accepts, by number of carriers
- Medicare8
- PPO8
- HMO7
- EPO4
- POS3
Source: Dmand AI Insurance Network Data
Sources for Dr. John Stephen Hammes'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) |
| Publications, topics and co-authors | PubMed (National Library of Medicine) (opens in a new tab)Dmand AI Research Linkage |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| Training, board certification and memberships | Dmand AI Professional Profile Data |
| Insurance carriers and plan types | Dmand AI Insurance Network 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. John Stephen Hammes
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. John Stephen Hammes' NPI number?
Dr. John Stephen Hammes' NPI number is 1891766994. It was assigned on January 28, 2006, and it is active in the NPI Registry.
What kind of doctor is Dr. John Stephen Hammes?
Dr. John Stephen Hammes is a nephrologist in San Diego, California. The primary specialty in the NPI Registry is Nephrology Physician (taxonomy code 207RN0300X).
Where does Dr. John Stephen Hammes practice?
Dr. Hammes practices at 720 Gateway Center Drive, Suite B, San Diego, CA 92102. Dr. Hammes' primary practice is Fresenius Kidney Care Gateway East in San Diego, California. Dmand AI also links Dr. Hammes to 2 hospitals, 3 group practices and clinics, 3 medical groups and 2 dialysis centers.
What is Dr. John Stephen Hammes' office phone number?
The practice phone on file for Dr. Hammes is (619) 264-4100.
What is Dr. John Stephen Hammes' medical license number?
Dr. Hammes' California license number on file is G84351.
Which hospitals is Dr. John Stephen Hammes affiliated with?
Dr. Hammes is affiliated with Scripps Mercy Hospital San Diego. Dmand AI links Dr. Hammes to 2 more hospitals.
What medical group is Dr. John Stephen Hammes part of?
Dr. Hammes is linked to UC San Diego Health. Dmand AI links Dr. Hammes to 3 more medical groups.
Does Dr. John Stephen Hammes accept Medicare?
Yes. CMS data shows Dr. Hammes billed Medicare for 2,257 services in 2024, and Dr. Hammes accepts Medicare assignment.
Does Dr. John Stephen Hammes offer telehealth?
Yes. The CMS Doctors and Clinicians file lists Dr. Hammes as offering telehealth services.
How many Medicare patients does Dr. John Stephen Hammes see?
CMS counts 432 Medicare patients who saw Dr. Hammes in 2024, with an average age of 72.
Show 9 more questionsShow fewer questions
Is Dr. John Stephen Hammes board certified?
Yes. Dr. Hammes is board certified in internal medicine by the American Board of Internal Medicine.
What services does Dr. John Stephen Hammes bill to Medicare?
In 2024, Dr. Hammes' most billed Medicare services were hospital inpatient care (99232), office visit, established patient (99214) and dialysis (90935).
Where did Dr. John Stephen Hammes go to medical school?
Dr. Hammes graduated from Uniformed Services University, F. Edward Hebert School of Medicine in 1993.
What drugs does Dr. John Stephen Hammes prescribe most?
In 2024 Medicare Part D data, Dr. Hammes' most prescribed drugs by claims were Furosemide, Losartan Potassium and Sevelamer Carbonate.
Has Dr. John Stephen Hammes received payments from drug or device companies?
CMS Open Payments shows $309 in general payments to Dr. Hammes from 8 companies from 2016 to 2024. The largest total came from OPKO Pharmaceuticals, LLC.
How long has Dr. John Stephen Hammes been practicing?
Dr. Hammes graduated from medical school in 1993, 33 years ago.
Does Dr. John Stephen Hammes do research?
Dmand AI links 5 publications to Dr. Hammes.
Who does Dr. John Stephen Hammes publish with?
Dr. Hammes' most frequent co-authors are Scott C. Thomson, MD (3 shared papers), Francis B. Gabbai, MD (2 shared papers) and John T. Bestoso, MD (1 shared paper).
What insurance does Dr. John Stephen Hammes accept?
Dr. Hammes is in network with 13 carriers, including Aetna, Blue Cross Blue Shield of Michigan and United Healthcare. Medicare plans come from the most carriers, 8. Check the plan with the practice before a visit.
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