Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor
Dr. Ivan Stephen Lowenthal, M.D.
Medical Oncology Physician in Tamuning, GU · enumerated 2006 · practices at Westpac Hematology & Oncology Center Inc.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1043245889
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Registry record
Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.
Taxonomy & licenses
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| 001187897 | Medicaid | CT | - |
| 18789 | Other | CT | CT. LICENSE |
| M-1925 | Other | GU | GUAM LICENSE |
| 06-1088532 | Other | - | TAX ID # |
| 1683 | Other | CT | CT CONTROLLED SUBSTANCE |
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 NPI 1043245889 active?
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Other providers at this practice address
Browse all →Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-03-19.