Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

Dr. Stephen M Nilsen, D.O.

Anesthesiology Physician in Nottingham, MD · enumerated 2005.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1972589398

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Registry record

Entity type Individual (Type 1)

Name Dr. Stephen M Nilsen

Credential D.O.

Sex Male

Practice address Nottingham, MD, 21236

Phone (855) 527-7246

Fax (866) 229-5063

Enumeration date Dec 17, 2005

Last updated in NPPES Jun 24, 2024

Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

207L00000X Anesthesiology Physician Allopathic & Osteopathic Physicians · License DO33153 (DC) Secondary

207L00000X Anesthesiology Physician Allopathic & Osteopathic Physicians · License H0058012 (MD) Primary

DO · Doctor of Osteopathic Medicine: A fully licensed physician trained in osteopathic medical schools, with the same practice rights as an MD. About the DO credential

Other identifiers

Identifier	Type	State	Issuer
699474101	Medicaid	MD	-

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

What specialty is Stephen Nilsen?

Stephen Nilsen is registered in NPPES with the primary taxonomy of Anesthesiology Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2024-06-24.