Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. John C Kortenber, OD

Optometrist in Algona, IA · enumerated 2006 · practices at John C. Kortenber Optometry PC.

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

National Provider Identifier

1821049586

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)

Name Dr. John C Kortenber

Credential OD

Sex Male

Practice address 112 N Thorington St, Algona, IA, 50511

Phone (515) 395-3937

Fax (515) 395-3938

Enumeration date May 15, 2006

Last updated in NPPES Mar 7, 2023

Taxonomy & licenses

152W00000X Optometrist Eye and Vision Services Providers · License 2002014339 (MO) Primary

OD · Doctor of Optometry: A licensed optometrist providing primary vision care, eye exams, and corrective lenses. About the OD credential

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

How do I verify John Kortenber's NPI record?

Cross-check NPI 1821049586 against the official CMS registry at npiregistry.cms.hhs.gov. This page mirrors the same public NPPES data with a monthly snapshot.

Is NPI 1821049586 active?

Yes, as of the latest NPPES snapshot, NPI 1821049586 is active (record last updated 2023-03-07).

Other providers at this practice address

Browse all →

John C. Kortenber Optometry PC Optometrist · Algona, IA NPI 1134172430

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2023-03-07.