2026 NPPES data Family Medicine Physician NPI 1558435123 MD
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STEPHEN LAMBERTON, MD

Family Medicine Physician in CUDAHY, Wisconsin. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
9K
Medicare Part D claims · 409 beneficiaries · Family Medicine Physician avg: 3K
Generic prescribing
89%
generic claims · 11% brand-name · higher generic rates reduce patient out-of-pocket costs
What the federal data reveals: STEPHEN LAMBERTON, MD is a Family Medicine Physician ([object Object]) practicing in CUDAHY, Wisconsin with a Medicare Part D prescribing footprint of 9K claims across 409 beneficiaries — 11% brand-name prescribing .

What stands out: STEPHEN LAMBERTON, MD filed 8,914 Medicare Part D claims in 2023 across CUDAHY, Wisconsin. Every figure on this page comes straight from federal CMS records, with no proprietary rating applied.

Board certification likely (heuristic — not verified)

STEPHEN LAMBERTON, MD practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation — signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).

STEPHEN LAMBERTON, MD at a glance

Quality data not reported

NPI registry status

Active

Issued 11/17/2006

NPI 1558435123

Primary specialty

Family Medicine Physician

High-volume

147,640 US NPIs in this specialty

Medicare Part D claims

8,914 161% vs specialty avg

2023 prescription claims

Specialty avg: 3,418

Specialty distribution in Wisconsin

How Family Medicine Physician compares to other specialties among Wisconsin providers

Wisconsin providers

Family Medicine Physician share within Wisconsin

1. Family Medicine Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Family Medicine Physician share within Wisconsin

Specialty board-certification context

Estimated specialty board-certified rate — Family Medicine Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Family Medicine Physician ABMS/AOA estimate

Est. board-certified rate (Family Medicine Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Family Medicine Physician) — ABMS / AOA estimate

The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.

Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).

STEPHEN LAMBERTON, MD is a Family Medicine Physician provider practicing in CUDAHY, Wisconsin, according to the CMS National Plan and Provider Enumeration System (NPPES). Credentials: MD. NPI: 1558435123. This profile includes practice location, specialty classification, and organizational affiliations from the CMS provider registry. Provider information is self-reported to CMS and updated monthly.

STEPHEN LAMBERTON, MD appears in the CMS NPPES registry as a Family Medicine Physician provider holding MD credentials at 5900 S. LAKE DRIVE, CUDAHY, WI, 53110, with a listed phone of (414) 489-4190. NPI 1558435123 was issued on 11/17/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what LAMBERTON most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 8,914 prescription claims written by this provider, covering 409 Medicare beneficiaries and totaling roughly $659K in drug spend, split 11% brand-name and 89% generic by claim count, with an opioid prescribing rate of 4.4%. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Family Medicine Physician is a high-volume specialty nationwide, with 147,640 enrolled providers across 56 states and an average of 3,418 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.

Practice Address

5900 S. LAKE DRIVE
CUDAHY, WI 53110

Provider Details

NPI 1558435123
Specialty Family Medicine Physician
Credentials MD
Gender Male
NPI Issued 11/17/2006

Hospital and facility affiliations

Facilities where STEPHEN LAMBERTON, MD bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" — a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.

LAKESHORE MEDICAL CLINIC LLC
CUDAHY, WI

Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).

Brand vs generic prescribing mix · Typical

STEPHEN LAMBERTON, MD — brand share 11.0%
Specialty average (est.)

11% brand-name claims vs 89% generic, on 8,914 2023 Medicare Part D claims.

The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.

Medicare Part D Prescribing Data

CMS Medicare Part D prescriber-level data for calendar year 2023.

8,914
Total Claims
$659K
Total Drug Cost
409
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
17,245
Total Day Supply
486,887
Brand vs Generic
11% brand / 89% generic
Brand Drug Cost
$476K
Generic Drug Cost
$180K
Opioid Claims
395 (4.4% rate)
Antibiotic Claims
368

Patient Demographics

Average Patient Age
73.4 years
Avg HCC Risk Score
1.32
Gender Split
55% female / 45% male
Age Distribution
<65: 41, 65-74: 186, 75-84: 128, 85+: 54

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

Drug Claims
Levothyroxine Sodium
314
Losartan Potassium
289
Pantoprazole Sodium
273
Gabapentin
266
Amlodipine Besylate
264
Atorvastatin Calcium
240
Potassium Chloride
204
Metoprolol Tartrate
198
Furosemide
194
Hydrocodone-Acetaminophen
Hydrocodone/Acetaminophen
189

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Family Medicine Physician Overview

How STEPHEN LAMBERTON, MD fits within the Family Medicine Physician landscape nationally.

147,640
Family Medicine Physician Providers in US
56
States with Family Medicine Physician
3,418
Avg Claims per Provider

STEPHEN LAMBERTON, MD's 8,914 claims are above the specialty average of 3,418.

Nearby Family Medicine Physician Providers in Wisconsin

Other clinicians with the same primary specialty enrolled in Wisconsin, drawn from the same CMS NPPES roster as LAMBERTON.

Compare Family Medicine Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is STEPHEN LAMBERTON, MD's specialty?
STEPHEN LAMBERTON, MD specializes in Family Medicine Physician and practices in CUDAHY, Wisconsin. Credentials: MD.
How much does STEPHEN LAMBERTON, MD prescribe under Medicare Part D?
In 2023, STEPHEN LAMBERTON, MD wrote 8,914 Medicare Part D claims totaling $659K in drug costs for 409 beneficiaries.
Where is STEPHEN LAMBERTON, MD located?
STEPHEN LAMBERTON, MD is located at 5900 S. LAKE DRIVE, CUDAHY, WI, 53110. Phone: (414) 489-4190.
What is STEPHEN LAMBERTON, MD's NPI number?
STEPHEN LAMBERTON, MD's National Provider Identifier (NPI) is 1558435123, issued on 11/17/2006.
Does STEPHEN LAMBERTON, MD prescribe more brand-name or generic drugs?
STEPHEN LAMBERTON, MD's prescribing is 11% brand-name and 89% generic drugs by claim count, with $476K in brand drug costs.
Does STEPHEN LAMBERTON, MD prescribe opioids?
Yes, STEPHEN LAMBERTON, MD had 395 opioid claims in 2023 with an opioid prescribing rate of 4.4%.
How many Family Medicine Physician providers are there in the US?
There are 147,640 Family Medicine Physician providers across 56 states in the US. The average Family Medicine Physician provider writes 3,418 Medicare Part D claims per year.
What drugs does STEPHEN LAMBERTON, MD prescribe most often?
Based on 2023 Medicare Part D data, STEPHEN LAMBERTON, MD's most frequently prescribed drugs include Levothyroxine Sodium, Losartan Potassium, Pantoprazole Sodium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does STEPHEN LAMBERTON, MD accept Medicare?
STEPHEN LAMBERTON, MD appears in CMS Medicare data with 8,914 Part D claims and 409 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify STEPHEN LAMBERTON, MD's credentials?
STEPHEN LAMBERTON, MD's NPI is 1558435123 with credentials MD. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.

Data Sources

Provider Directory
CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
Specialty Classification
NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
Prescribing Data
CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
Limitations
Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.

See our complete data methodology for details on how we collect and process government data.

Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).

Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology