Quick answers
- Does Maria Kostantacos accept Medicare assignment?
- Yes. Medicare's clinician data says Maria Kostantacos accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- How many Medicare patients does Maria Kostantacos see?
- In 2024, CMS data shows 98 Original Medicare patients and 283 services for Maria Kostantacos. This counts Original Medicare only and measures volume, not quality.
- What is Maria Kostantacos's NPI number?
- 1538493614. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Maria Kostantacos, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 98 |
|---|---|
| Services billed to Medicare | 283 |
| Different services or procedures | 10 |
| Participating Medicare provider | Yes |
| Average age of these patients | 75 |
Most frequent services
- Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes (99232)127 services
- Subsequent hospital care with straightforward or low level of medical decision making, per day, if using time, at least 25 minutes (99231)71 services
- Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes (99222)26 services
- Initial hospital care with straightforward or low level of medical decision making, per day, if using time, at least 40 minutes (99221)22 services
- Hospital discharge day management, 30 minutes or less (99238)20 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High blood pressure75%
- High cholesterol75%
- Arthritis56%
- Depression46%
- Anxiety44%
- Ischemic heart disease39%
Hospitals where Maria Kostantacos works
Medicare's Facility Affiliation Data lists Maria Kostantacos at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Mercy Health System CorpJanesville, WI · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 520066
Practice locations
Addresses where Maria Kostantacos is enrolled with Medicare (CMS data updated October 2, 2026).
- 1001 Grant StHarvard, IL 60033 (815) 943‑8090
- 1010 N Washington StJanesville, WI 53548 (608) 741‑2430
- 510 N Terrace StJanesville, WI 53548 (608) 756‑7277
Group practices
Medicare enrollment lists Maria Kostantacos as a member of this group (CMS data updated October 2, 2026).
- Mercy Health System Corporation753 clinicians in the group
Specialties
- Nurse Practitionerprimary
Other nurse practitioners in Illinois
Clinicians with the same Medicare primary specialty in Illinois — not a recommendation.
Other clinicians in Mercy Health System Corporation
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Graduation year | 2013 |
|---|---|
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1538493614 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians