Quick answers
- Does Kristina T. Grehan accept Medicare assignment?
- Yes. Medicare's clinician data says Kristina T. Grehan 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 Kristina T. Grehan see?
- In 2024, CMS data shows 12 Original Medicare patients and 15 services for Kristina T. Grehan. This counts Original Medicare only and measures volume, not quality.
- What is Kristina T. Grehan's NPI number?
- 1992138218. 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 Kristina T. Grehan, 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 | 12 |
|---|---|
| Services billed to Medicare | 15 |
| Different services or procedures | 4 |
| Participating Medicare provider | Yes |
| Average age of these patients | 81 |
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%
- Ischemic heart disease75%
Practice locations
Addresses where Kristina T. Grehan is enrolled with Medicare (CMS data updated October 2, 2026).
- 48 Route 25aSmithtown, NY 11787 (631) 751‑3000
Group practices
Medicare enrollment lists Kristina T. Grehan as a member of this group (CMS data updated October 2, 2026).
- North Shore Hematology Oncology Associates PC479 clinicians in the group
Specialties
- Nurse Practitionerprimary
Other nurse practitioners in Smithtown
Clinicians with the same Medicare primary specialty in Smithtown, NY — not a recommendation.
Other clinicians in North Shore Hematology Oncology Associates PC
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) | 1992138218 |
| 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
- 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