Dr. Theresa Thanh Nguyen, M.D.
What this data tells you about Dr. Nguyen
Dr. Theresa Thanh Nguyen is an internal medicine specialist in Westminster, CA, with 20 years of NPI registration. Based on federal Medicare data, Dr. Nguyen performed 3,839 Medicare services across 1,702 unique beneficiaries.
Between the years covered by Open Payments, Dr. Nguyen received a total of $10,487 from 51 pharmaceutical and/or device companies across 345 individual payments. These payments are legal, publicly disclosed under the federal Sunshine Act, and common in internal medicine. Most payments are for meals and travel — low-value interactions common across virtually all practicing physicians. Patients may wish to discuss these relationships with their provider.
The Data Coverage level for Dr. Nguyen is Very High — reflecting how much public federal data is available about this provider. Patients are encouraged to use this data as one of several factors when choosing a healthcare provider.
Medicare Practice Summary
Medicare Utilization ↗Top procedures by volume
Ranked by number of services performed for Medicare patients. Avg. submitted charge is what the provider billed; avg. Medicare payment is what CMS paid.
| Procedure | Volume | Avg. paid | Avg. submitted |
|---|---|---|---|
| Office visit, established patient (20-29 min) An office visit for an existing patient lasting between 20 and 29 minutes. The visit involves medical evaluation and management of the patient's condition. |
1,599 | $68 | $150 |
| Blood draw (venipuncture) Insertion of a needle into a vein to collect a blood sample. |
746 | $8 | $40 |
| Chronic care management, first 20 min/month This service covers the first 20 minutes of clinical staff time directed by a healthcare professional each calendar month to manage chronic conditions. |
695 | $47 | $100 |
| Flu vaccine administration This procedure involves the administration of the influenza virus vaccine. It covers the process of delivering the vaccine to the patient. |
222 | $33 | $40 |
| Annual wellness visit, follow-up A follow-up annual wellness visit that includes a personalized prevention plan of service. |
207 | $140 | $221 |
| Quadrivalent influenza vaccine, cell-culture derived A flu shot containing four strains of influenza virus, produced using cell culture technology rather than eggs. This formulation is free from preservatives and antibiotics. |
189 | $33 | $50 |
| Drug injection, under skin or into muscle A procedure involving the administration of a medication or substance via injection into the subcutaneous tissue or muscle. |
37 | $9 | $69 |
| Annual wellness visit, initial visit A yearly appointment to review your health and create a personalized prevention plan. This initial visit focuses on preventive care and health assessment. |
35 | $178 | $239 |
| Quadrivalent influenza vaccine, preservative-free A flu shot containing four strains of the influenza virus, formulated without preservatives, administered in a 0.5 ml dose. |
31 | $22 | $50 |
| Electrocardiogram (EKG), 12-lead A standard heart rhythm test using at least 12 leads to record electrical activity. A healthcare provider interprets the results and provides a written report. |
24 | $11 | $85 |
| Pneumonia vaccine administration This procedure involves the injection of a vaccine to protect against pneumococcal disease. It is administered by a healthcare provider. |
22 | $33 | $40 |
| Pneumococcal conjugate vaccine (PCV20) An intramuscular injection of the 20-valent pneumococcal conjugate vaccine. It is used to protect against diseases caused by Streptococcus pneumoniae bacteria. |
21 | $280 | $367 |
| New patient office visit (30-44 min) An initial office visit for a new patient lasting between 30 and 44 minutes. This code is used when the total time spent on the date of the encounter falls within this range. |
11 | $81 | $250 |
Industry Payment Transparency
Open Payments through 2024 ↗Payment profile
Industry payments classified by relationship type. Not all payments are equal — research and consulting reflect different relationships than speaking programs or meals.
Payment trend by year
Annual totals from pharmaceutical and medical device companies.
Payments by company (2024)
All-time payments by company (2018-2024) ›
Associated products mentioned in payments ›
Most payments (99%) are for meals and travel — low-value interactions that are common across virtually all practicing physicians. Total industry engagement is in the top 9% for internal medicine in CA.
Geographic Context
2.2 mi
Data Sources
| Provider Registry | ✓ NPPES | Weekly updates |
| Medicare Enrollment | ✓ PECOS | Monthly updates |
| Practice Data | ✓ Medicare Util. | Annual (CY lag) |
| Industry Payments | ✓ Open Payments | CY 2024 |
| Disciplinary History | — Not public | N/A |
This provider has data in 4 of 4 available federal datasets, with a Data Coverage level of Very High. This reflects how much public data is available about a provider. How we calculate this →
Summary
Dr. Nguyen is a clinical cardiology specialist, with above-average Medicare volume (top 8% in CA), with low-engagement industry engagement in the top 9% of CA peers, with 20 years of NPI registration.
This summary is auto-generated from federal data, describing data availability and patterns. Read our methodology →
Frequently Asked Questions
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All data on this page is sourced verbatim from public federal records published by the U.S. Centers for Medicare & Medicaid Services (CMS): NPPES ↗, Open Payments ↗, Medicare Provider Utilization ↗, and PECOS. Publication is mandated by the Physician Payments Sunshine Act (§6002 ACA, 42 U.S.C. §1320a-7h) and the Freedom of Information Act.
This page is not medical advice, an endorsement, a recommendation, or a quality rating. Data Coverage reflects data completeness — how much federal information exists for this provider — not clinical performance, patient outcomes, or quality of care. Always verify information directly with the provider and consult a licensed clinician before making medical decisions.
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