Dr. Catherine Michels Alonzo, MD
- Medicare services, 2022
- 3,448
- Part D claims, 2023
- 250
- Industry payments
- $2,919
- Affiliated sites
- 2
- Medical groups
- 2
- Practice address
- 49 Lake Ave, Greenwich, CT 06830
- Practice phone
- Call (203) 869-1285
- Professional email
- Get professional email
- Personal email
- Get personal email
- Mobile number
- Get mobile number
Primary practice
Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave)
Surgical practice · Greenwich, Connecticut
Find Dr. Alonzo's professional email, personal email and mobile number
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Dr. Catherine Michels Alonzo is a urologist in Greenwich, Connecticut
Dr. Alonzo practices at Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave) in Greenwich, Connecticut.
Dr. Alonzo's NPI, 1770802357, was assigned on May 22, 2010. Dr. Alonzo holds Connecticut license 49084.
- NPI
- 1770802357NPI Registry (opens in a new tab)
- NPI enumeration date
- May 22, 2010
- NPI status
- Active
- Practice phone
- (203) 869-1285
- Professional email
- Get email
- Personal email
- Get email
- Mobile number
- Get number
- Sex
- Female
- Estimated age
- 49
- Medical school graduation
- 2003
Sources: NPPES NPI Registry (CMS); Dmand AI Professional Profile Data; Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Dr. Catherine Michels Alonzo practices at 2 locations in Greenwich, Connecticut
Dr. Alonzo's primary practice is Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave), at 49 Lake Ave, Greenwich, CT 06830. The practice phone is (203) 869-1285. The NPI Registry lists Dr. Alonzo's practice address as 5 Perryridge Rd, Greenwich, CT 06830.
- Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave)Primary49 Lake Ave, Greenwich, CT 06830Phone(203) 869-1285
- NPI Registry address5 Perryridge Rd, Greenwich, CT 06830 · Western Ct CountyPhone(203) 869-1285
Sources: NPPES NPI Registry (CMS); Dmand AI Affiliation Data; Doctors and Clinicians National Downloadable File (CMS); and Dmand AI Practice Data
Dr. Catherine Michels Alonzo is affiliated with 2 sites of care and 2 medical groups
Dr. Alonzo's primary practice is Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave) in Greenwich, Connecticut. The medical group on file is Yale Health. Dmand AI also links Dr. Alonzo to 1 more group practice or clinic and 1 medical group, each named with a free account.
Sources: Dmand AI Affiliation Data; and Doctors and Clinicians National Downloadable File (CMS)
Dmand AI tracks the EHR system at Dr. Catherine Michels Alonzo's practice
Dmand AI tracks the electronic health record (EHR) system at each site where Dr. Alonzo practices, 2 sites in all. Vendor and product names are available with a free account.
| Site | EHR vendor and product |
|---|---|
| Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave) | Available with a free account |
| +1 more site and 1 medical group | Available with a free account |
Source: Dmand AI Technology Install Data
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Dr. Catherine Michels Alonzo is one of 161 urologists in Connecticut
Urology is Dr. Alonzo's primary specialty in the NPI Registry, under taxonomy code 208800000X. Dmand AI has Dr. Alonzo's licenses on file in 2 states: Connecticut and New York.
Specialties and state licenses
- Urology, ConnecticutPrimary
- New York license
Urologists near Dr. Alonzo
Counts of urologists 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. Catherine Michels Alonzo billed Medicare for 3,448 services in 2022
CMS data shows 3,448 Medicare services from Dr. Alonzo across 18 procedure codes in 2022. Medicare paid $119,482 for them.
Dr. Alonzo's Medicare services by type, 2021 to 2022
- 2021
- 2022
- Drugs given in the office
- 2021: 02022: 1,336
- Lab and pathology
- 2021: 1,0552022: 80124%
- Office and hospital visits
- 2021: 9732022: 68330%
- Surgery
- 2021: 7902022: 60024%
- Imaging
- 2021: 292022: 283%
Where Dr. Alonzo's Medicare services took place, 2022
- In an office3,42399%
- In a facility251%
Dr. Alonzo compared with the Connecticut median for urologists, 2022
- Dr. Alonzo
- Connecticut median
- Medicare services
- 3,448vs 9603.6 times
- Part D claims
- 250vs 89872% below
Medians across 158 urologists in Connecticut with Dmand AI profiles that report each measure.
Dr. Alonzo'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. Alonzo?
Medicare shows one payer. Book a meeting to get commercial claims data for Dr. Alonzo and other urologists in Connecticut.
Sources: Medicare Physician & Other Practitioners - by Provider and Service (CMS), 2024 data; and Dmand AI Peer Benchmarks
Dr. Catherine Michels Alonzo's patients have a median age of 74
Across all payers, Dmand AI patient panel data puts Dr. Alonzo's median patient age at 74, with 57% women.
Dr. Alonzo's patients across all payers
Dmand AI patient panel data covers Medicare, Medicaid and commercial patients.
Patient panel by age, all payers
Median age 74
Patient panel by sex, all payers
- Women57%
- Men41%
Source: Dmand AI Patient Panel Data
Dr. Catherine Michels Alonzo wrote 250 Medicare Part D claims in 2023
In 2023, Dr. Alonzo wrote 250 Medicare Part D claims. They cover 8 drugs, with $64,194 in total drug cost. In 2022, CMS named 2,011 claims across 24 drugs.
Dr. Alonzo's most prescribed drugs by claims, 2023
CMS names a drug when it has 11 or more claims. Share is of the claims for drugs CMS names.
Part D claims for drugs CMS names, 2022 to 2023
- 2022
- 2023
- Claims for drugs CMS names
- 2022: 2,0112023: 25088%
Drugs named by CMS: 8 in 2023, 24 in 2022.
Source: Medicare Part D Prescribers - by Provider and Drug (CMS), 2024 data, released May 6, 2026
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Dr. Catherine Michels Alonzo received $2,919 in industry payments from 2016 to 2022
CMS Open Payments shows 160 general payments to Dr. Alonzo from 28 drug and device companies from 2016 to 2022. Food and beverage make up the largest share, 92% of the total. Astellas Pharma US Inc paid the most, $735.
General payments to Dr. Alonzo by program year, 2016 to 2022
General payments to Dr. Alonzo by kind, 2016 to 2022
- Food and beverage$2,67492%
- Education$2458%
Companies that paid Dr. Alonzo the most, 2016 to 2022
Share is of all general payments to this clinician.
Source: Open Payments (CMS), 2025 data, released July 7, 2026
Sources for Dr. Catherine Michels Alonzo'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 | NPPES NPI Registry (CMS) (opens in a new tab)Dmand AI Affiliation DataDoctors and Clinicians National Downloadable File (CMS) (opens in a new tab)Dmand AI Practice Data |
| Primary practice, affiliations and health system | Dmand AI Affiliation DataDoctors and Clinicians National Downloadable File (CMS) (opens in a new tab) |
| 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) |
| Industry payments | Open Payments (CMS) (opens in a new tab) |
| 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. Catherine Michels Alonzo
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What is Dr. Catherine Michels Alonzo's NPI number?
Dr. Catherine Michels Alonzo's NPI number is 1770802357. It was assigned on May 22, 2010, and it is active in the NPI Registry.
What kind of doctor is Dr. Catherine Michels Alonzo?
Dr. Catherine Michels Alonzo is a urologist in Greenwich, Connecticut. The primary specialty in the NPI Registry is Urology Physician (taxonomy code 208800000X).
Where does Dr. Catherine Michels Alonzo practice?
Dr. Alonzo practices at 49 Lake Ave, Greenwich, CT 06830. Dr. Alonzo also practices at 5 Perryridge Rd, Greenwich, CT 06830. Dr. Alonzo's primary practice is Yale Health Center - Urology & Nephrology - Greenwich (Lake Ave) in Greenwich, Connecticut. Dmand AI also links Dr. Alonzo to 1 group practice or clinic and 1 medical group.
What is Dr. Catherine Michels Alonzo's office phone number?
The practice phone on file for Dr. Alonzo is (203) 869-1285.
What is Dr. Catherine Michels Alonzo's medical license number?
Dr. Alonzo holds Connecticut license 49084, one of the licenses on file in 2 states.
Which states has Dr. Catherine Michels Alonzo been licensed in?
Dmand AI has state licenses on file for Dr. Alonzo in Connecticut and New York.
What medical group is Dr. Catherine Michels Alonzo part of?
Dr. Alonzo is linked to Yale Health. Dmand AI links Dr. Alonzo to 1 more medical group.
Does Dr. Catherine Michels Alonzo accept Medicare?
Yes. CMS data shows Dr. Alonzo billed Medicare for 3,448 services in 2022.
What services does Dr. Catherine Michels Alonzo bill to Medicare?
In 2022, Dr. Alonzo's most billed Medicare services were injected or infused drug (J9030), lab and pathology test (81002) and office visit, established patient (99213).
What drugs does Dr. Catherine Michels Alonzo prescribe most?
In 2023 Medicare Part D data, Dr. Alonzo's most prescribed drugs by claims were Myrbetriq, Tamsulosin HCl and Dutasteride.
Has Dr. Catherine Michels Alonzo received payments from drug or device companies?
CMS Open Payments shows $2,919 in general payments to Dr. Alonzo from 28 companies from 2016 to 2022. The largest total came from Astellas Pharma US Inc.
How long has Dr. Catherine Michels Alonzo been practicing?
Dr. Alonzo graduated from medical school in 2003, 23 years ago.
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