Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Mary Dawn Sienkiewicz, ARNP
Nurse Practitioner in Bellevue, WA · enumerated 2007.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1245413533
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Registry record
Entity type Individual (Type 1)
Name Mary Dawn Sienkiewicz
Credential ARNP
Sex Female
Practice address 1231 116th Ave Ne Ste 950, Bellevue, WA, 98004
Phone (206) 328-7734
Enumeration date Dec 10, 2007
Last updated in NPPES Nov 29, 2018
Taxonomy & licenses
363L00000X Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License AP30007980 (WA) Primary
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| 1089427 | Medicaid | WA | - |
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.
Frequently asked questions
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.
What specialty is Mary Sienkiewicz?
Mary Sienkiewicz is registered in NPPES with the primary taxonomy of Nurse Practitioner. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.
Other providers at this practice address
Browse all → Jean Chakraborty Obstetrics & Gynecology Physician · Bellevue, WA NPI 1568690345 Jennifer Brown-Ramos Women's Health Nurse Practitioner · Bellevue, WA NPI 1063644912 Sarah Bienenfeld Obstetrics & Gynecology Physician · Bellevue, WA NPI 1134418247 Jemma Nonog Advanced Practice Midwife · Bellevue, WA NPI 1285155044 Megan Crenshaw Obstetrics & Gynecology Physician · Bellevue, WA NPI 1336728922
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2018-11-29.