Mark Cassellius, D.C.
NPI 1669433462 · Chiropractor · Onalaska, WI
Enrolled with Medicare as Practitioner - Chiropractic · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Mark Cassellius, D.C. is a Chiropractor provider in Onalaska, WI (NPI 1669433462).
Provider details
- NPI number
- 1669433462
- Entity type
- Individual
- Primary specialty
- ChiropractorChiropractic Providers
- Credential
- D.C.
- Sex
- Male
- Sole proprietor
- Yes
- License
- 2293 (WI)
Specialties & taxonomies
Chiropractic Providers
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
20 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-03-31
- Last updated
- 2011-04-26
Frequently asked questions
- What is Mark Cassellius's NPI number?
- Mark Cassellius's National Provider Identifier (NPI) is 1669433462, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Mark Cassellius's specialty?
- Mark Cassellius is listed in the NPPES registry with a primary specialty of Chiropractor (Chiropractic Providers).
- Where is Mark Cassellius located?
- Mark Cassellius's practice location on file with NPPES is 419 Sand Lake Rd, Onalaska, WI 54650-2706.
- What is Mark Cassellius's phone number?
- The practice phone number listed in the NPPES registry for Mark Cassellius is (608) 783-3307.
- Does Mark Cassellius accept Medicare?
- Mark Cassellius is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Mark Cassellius's NPI active?
- Yes — Mark Cassellius's NPI (1669433462) is active in the NPPES registry as of the last update on 2011-04-26.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.