Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Theresa Guinther-Mulders, DO

Pediatrics Physician in Bay City, MI · enumerated 2008.

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

National Provider Identifier

1326206020

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Registry record

Entity type Individual (Type 1)

Name Theresa Guinther-Mulders

Credential DO

Sex Female

Practice address 3884 Monitor Rd, Bay City, MI, 48706

Phone (989) 671-2000

Fax (989) 671-4000

Enumeration date May 29, 2008

Last updated in NPPES Oct 14, 2022

Taxonomy & licenses

208000000X Pediatrics Physician Allopathic & Osteopathic Physicians · License 5101017610 (MI) 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
70350	Other	MI	MERIDIAN HEALTH PLAN
5320043	Other	MI	BCBSM

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 Theresa Guinther-Mulders?

Theresa Guinther-Mulders is registered in NPPES with the primary taxonomy of Pediatrics 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 2022-10-14.