Dr. Nathan Philip Seigrist , DO
General Practice β’ O Fallon, IL
3 Saint Elizabeth Blvd Ste 4000
O Fallon, IL 622691284
This profile restates public CMS/NPPES data; T-MedInfo gives no medical advice — consult a licensed professional, and call 911 for emergencies.
Practice Location & Contact Primary Location
3 Saint Elizabeth Blvd Ste 4000
O Fallon, IL 622691284
Matched by practice address or phone in NPPES. A shared address or phone does not confirm that this clinician works there.
What Public CMS Data Show
General Practice: NPPES taxonomy is a reported classification, not proof of board certification.
Industry payments (Open Payments)
Fewer than 11 payment records totaling $31.94 in 2025
Drug and medical device companies must report certain payments to doctors and some other clinicians to CMS, such as meals, travel, speaking fees or research funding.
It shows reported financial ties between this clinician and companies. You can ask your clinician about them.
These records are submitted by drug and medical device companies, and a reported payment does not necessarily mean the financial relationship is improper.
General: payments not tied to research, such as meals, travel, consulting or speaking fees.
A reported payment does not necessarily mean the financial relationship is improper. Research payments can go to a hospital or university for a study the clinician leads, not to the clinician personally. Clinicians can dispute records with the company that reported them.
Source: CMS Open Payments, program year 2025.
NPI first issued
2023
The year this clinician's National Provider Identifier (NPI) was issued. An NPI is a unique 10-digit ID that US health care providers use for billing.
What this does not show: NPI first issued
NPIs have been issued only since 2005, so this year is not necessarily when the clinician started practicing.
Source: CMS NPPES NPI Registry.
Medicare assignment not listed
CMS data do not show whether this clinician accepts Medicare assignment. This does not mean they do not accept Medicare. Ask the office.
Medicare assignment applies to Original Medicare. It does not tell you whether the clinician is in a Medicare Advantage plan's network, accepts other insurance, or is taking new patients.
Source: CMS Doctors and Clinicians; Medicare.gov, βDoes your provider accept Medicare as full payment?β
No telehealth indicator
CMS shows this indicator only when recent Medicare claims include telehealth services. The clinician may still offer telehealth; ask the office.
Source: CMS, Telehealth Indicator on Medicare Care Compare (fact sheet, January 2023); CMS Doctors and Clinicians.
Enrolled in Medicare (PECOS)
Dr. Seigrist has a Medicare enrollment record in PECOS, the CMS system clinicians use to enroll so they can bill Medicare or order services for people with Medicare.
It does not show whether the clinician accepts assignment, is in your plan's network, or is taking new patients.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Can order Medicare-covered services
CMS lists Dr. Seigrist as eligible to order or refer Medicare Part B clinical laboratory and imaging services, durable medical equipment (DME) and home health services for people with Medicare.
Medicare pays for these items and services only when they are ordered by an eligible clinician.
What this does not show: Can order Medicare-covered services
It does not mean the clinician offers these services directly.
Source: CMS Medicare Fee-For-Service Public Provider Enrollment (PECOS); CMS Order and Referring file.
Compared with the same specialty in O Fallon and Illinois
5 active clinicians are listed under General Practice with a practice address in O Fallon, IL (291 in Illinois).
Addresses are self-reported to NPPES and may be out of date.
CMS data by year
Changes may reflect reporting, coverage or privacy limits, not changes in care quality.
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Industry payments (Open Payments)
CMS data for industry payments (Open Payments) are available for 2025 only.
Sources: CMS Open Payments (2025), CMS Doctors and Clinicians, CMS NPPES NPI Registry. Specialty names follow the NUCC Health Care Provider Taxonomy.
Text: T-MedInfo Β· Report an error.
Pharma & Medical Device Financial Disclosures
Payments and other transfers of value that drug and medical device companies reported to CMS Open Payments
Program year 2025 (payments made January 1 β December 31, 2025): fewer than 11 records totaling $31.94.
| Manufacturer | Payment Nature | Product | Type | Amount ($) |
|---|---|---|---|---|
| AstraZeneca Pharmaceuticals LP |
Food and Beverage
In-kind items and services
|
BREZTRI | General | $31.94 |
Source: CMS Open Payments, program year 2025, released June 30, 2026.
Specialties & License Numbers Reported to NPPES
Self-certified to NPPES: 2026-06-24NUCC Taxonomy Code: 208D00000X
A physician who specializes in the general practice of diagnosing, treating, and managing patients with a variety of illnesses and conditions.
NUCC Taxonomy Code: 171000000X
Active duty military health care providers not otherwise classified who need to be separately identified for operational, clinical, or administrative processes.
NUCC Taxonomy Code: 390200000X
An individual who is enrolled in an organized health care education/training program leading to a degree, certification, registration, and/or licensure to provide health care.
Medicare (PECOS) Enrollment & Ordering Eligibility
Source: CMS PECOSORDER AND REFERRING ONLY - FAMILY PRACTICE
I20241202002041
IL
6406381383
Sources: CMS Provider Enrollment and Order and Referring. Medicare enrollment is a billing status, not an accreditation or quality rating.
Clinicians Sharing This Practice Address or Phone
Clinicians sharing this NPPES address, phone or fax; a shared contact does not mean they work together.
Physician Assistant
JANEAUXIER, Physician Assistant (Certified)
Internal Medicine
Doctor of Medicine (M.D.)
Family Medicine
Doctor of Osteopathic Medicine (D.O.)
Family Medicine
Doctor of Osteopathic Medicine (D.O.)
Pharmacist
Doctor of Pharmacy (Pharm.D.)
Obstetrics & Gynecology
Doctor of Osteopathic Medicine (D.O.)
Career & Practice History Timeline
Changes recorded in monthly NPPES data files: addresses, names, credentials, specialties and NPI status
Registered at 3 SAINT ELIZABETH BLVD STE 4000, O FALLON, IL 622691284 (Tel: 6182569355)
Registered at 3 SAINT ELIZABETH BLVD STE 4000, O FALLON, IL 622691284 (Tel: 6182569355)
Registered at 3551 ROGER BROOKE DR, FORT SAM HOUSTON, TX 782344504 (Tel: 2109164141)
Registered at 4306 LORING PARK, CONVERSE, TX 781093747 (Tel: 9726584680)
Recorded as NATHAN SEIGRIST, DO
Military Health Care Provider
NPI status registered as active in NPPES database
Registered at 5000 LAKEWOOD RANCH BLVD, BRADENTON, FL 342114909 (Tel: 9726584680)
Registered at 4511 SUMMER COVE DR E APT 423, SARASOTA, FL 342434978 (Tel: 9726584680)
Recorded as NATHAN SEIGRIST
Student in an Organized Health Care Education/Training Program
First registered as active Individual Practitioner in NPPES Database.
NPI Administrative Meta
Mailing Address
3 Saint Elizabeth Blvd Ste 4000
O Fallon, IL 622691284
Phone: 6182569355