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DR. THOMAS S LAM M.D.
NPI 1437185295
Internal Medicine - Gastroenterology in Alhambra, CA

Active since June 24, 2006PECOS EnrolledAccepts Medicare Assignment
333 S GARFIELD AVE STE A, ALHAMBRA, CA 91801(626) 284-1997(626) 284-2549 Get Directions Write a Review

NPPES record last updated: June 17, 2025. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Jun 17, 2025, Jun 16, 2018 (2 updates tracked since 2018).

About Dr. Thomas S Lam M.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DR. THOMAS S LAM M.D. (NPI 1437185295) is an individual gastroenterology provider in Alhambra, California, licensed in California (A44280) and active in the NPI registry since June 2006. He is enrolled in Medicare PECOS and is a graduate of Other (1981).

NPPES Registry Identity

NPI1437185295
Entity TypeIndividualMale
Primary Taxonomy207RG0100X
Provider Legal NameDR. THOMAS S LAMCredential: M.D.
Location Address333 S GARFIELD AVE STE AAlhambra, CA 91801-3895
Mailing AddressPo Box 7589Alhambra, CA 91802-7589 · (626) 284-1997 · Fax (626) 284-2549
Phone(626) 284-1997
Fax(626) 284-2549
Sole ProprietorNo
Medical School CMSOtherGraduated 1981
Enumeration DateJune 24, 2006
Last NPPES UpdateJune 17, 20252 updates tracked since enumeration
NPPES CertifiedJune 17, 2025
✔ NPI 1437185295 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal Medicine · GastroenterologyAllopathic & Osteopathic Physicians
Taxonomy Code207RG0100X
License✔ Licensed in CA · A44280
Definition
An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This specialist treats conditions such as abdominal pain, ulcers, diarrhea, cancer and jaundice and performs complex diagnostic and therapeutic procedures using endoscopes to visualize internal organs.
333 S GARFIELD AVE STE A, Alhambra, CA 91801
Open in Google Maps ↗

Other Identifiers 2

Medicaid00A442800CA
Medicaid00A442801CA

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Dr. Thomas S Lam M.d. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.

PECOS PAC ID4284621731
PECOS Enrollment IDI20040727001651
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignments

2

Medicare enrollment records show Thomas Lam reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Amg, A Professional Medical Corporation
1.6 mi
Internal Medicine
1658 W VALLEY BLVD STE 120
Alhambra, CA 91803
  • Reassigned Medicare billing, California enrollment
  • 48 clinicians in this Medicare group
NPI 1558306266 (626) 282-0282
1 World Medicine Urgent Care Corp
2.0 mi
Urgent Care
120 W HELLMAN AVE, SUITE 101
Monterey Park, CA 91754
  • Reassigned Medicare billing, California enrollment
  • 2 clinicians in this Medicare group
NPI 1790188290 (626) 282-0261

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Areas of Expertise CMS Part B claims 7

Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.

Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more 99213
This is a routine visit for patients who have already been seen by the healthcare provider. During this approximately 20-29 minute appointment, your health status will be evaluated and any necessary treatments or tests will be discussed. It's a chance to address any health concerns you may have.
192 services130 patients
New patient office or other outpatient visit with low level of medical decision making, if using time, 30 minutes or more 99203
This service involves an initial office or outpatient visit for a new patient. The healthcare professional will spend 30-44 minutes understanding your health history, current issues, and discussing possible treatment plans. It's a comprehensive evaluation to start your healthcare journey.
65 services65 patients
Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope 43239
This procedure involves using a thin, flexible tube with a light and camera, known as an endoscope, to examine the esophagus, stomach, and upper part of the small intestine. Small tissue samples are taken for further examination to help diagnose various conditions.
26 services26 patients
Biopsy of large bowel using a flexible endoscope 45380
A biopsy of the large bowel using a flexible endoscope is a procedure where a thin, flexible tube with a camera is inserted through the rectum to examine the bowel. If abnormal tissue is found, a small sample is taken for further examination. This helps in diagnosing conditions like inflammation, polyps, or cancer.
21 services21 patients
Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope 43239
This procedure involves using a thin, flexible tube with a light and camera, known as an endoscope, to examine the esophagus, stomach, and upper part of the small intestine. Small tissue samples are taken for further examination to help diagnose various conditions.
15 services14 patients
Biopsy of large bowel using a flexible endoscope 45380
A biopsy of the large bowel using a flexible endoscope is a procedure where a thin, flexible tube with a camera is inserted through the rectum to examine the bowel. If abnormal tissue is found, a small sample is taken for further examination. This helps in diagnosing conditions like inflammation, polyps, or cancer.
15 services14 patients

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 91801 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$142.39 typical visit price
range $62.96 – $187.60
Typical copayment $35.59 (range $15.74 – $46.90)
Most-billed visit code 99204
Established Patient
$109.96 typical visit price
range $20.84 – $153.61
Typical copayment $27.49 (range $5.21 – $38.40)
Most-billed visit code 99214
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Other Providers at the Same Location NPPES 4

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

THOMAS S.LAM MD. A PROFESSIONAL CORPORATION
Internal Medicine (Gastroenterology)
333 S GARFIELD AVE STE A
ALHAMBRA, CA 91801
Los Angeles County (626) 284-1997
AMG, A PROFESSIONAL MEDICAL CORPORATION
Internal Medicine (Gastroenterology)
333 S GARFIELD AVE STE A
ALHAMBRA, CA 91801
Los Angeles County (626) 289-7333
TIANYUAN YANG NP
Nurse Practitioner (Family)
333 S GARFIELD AVE STE A
ALHAMBRA, CA 91801
Los Angeles County (626) 284-1997
SUNNY WONG MD
Internal Medicine (Gastroenterology)
333 S GARFIELD AVE STE A
ALHAMBRA, CA 91801
Los Angeles County (626) 284-1997

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Thomas Lam's NPI number?

The NPI number for Thomas Lam is 1437185295. It was assigned to this individual provider in the NPPES registry on June 24, 2006.

Where is Thomas Lam located?

Thomas Lam practices at 333 S Garfield Ave Ste A, Alhambra, CA 91801. The listed phone number is (626) 284-1997.

What is Thomas Lam's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Gastroenterology, with taxonomy code 207RG0100X.

Is Thomas Lam enrolled in Medicare?

Yes. Thomas Lam is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.

Which organizations bill Medicare for Thomas Lam's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Thomas Lam reassigns Medicare benefits to 2 organizations: Amg, A Professional Medical Corporation (Alhambra, CA) and 1 World Medicine Urgent Care Corp (Monterey Park, CA). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Thomas Lam's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

When was this NPI record last updated?

The NPPES record for Thomas Lam was last updated on June 17, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 16 months ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.