Quick answers
- Does Gunnlaugur P. Nielsen accept Medicare assignment?
- Yes. Medicare's clinician data says Gunnlaugur P. Nielsen 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 Gunnlaugur P. Nielsen see?
- In 2024, CMS data shows 852 Original Medicare patients and 2,230 services for Gunnlaugur P. Nielsen. This counts Original Medicare only and measures volume, not quality.
- What is Gunnlaugur P. Nielsen's NPI number?
- 1174592653. 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 Gunnlaugur P. Nielsen, 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 | 852 |
|---|---|
| Services billed to Medicare | 2,230 |
| Different services or procedures | 22 |
| Participating Medicare provider | Yes |
| Average age of these patients | 72 |
Most frequent services
- Preparation of tissue for examination by removing any calcium present (88311)512 services
- Pathology examination of tissue using a microscope, intermediate complexity (88305)356 services
- Special stained specimen slides to examine tissue, each additional procedure (88341)318 services
- Pathology examination of tissue using a microscope, moderately low complexity (88304)288 services
- Pathology examination of tissue using a microscope, moderately high complexity (88307)262 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%
- Arthritis69%
- Anxiety37%
- Ischemic heart disease35%
- Chronic kidney disease33%
Hospitals where Gunnlaugur P. Nielsen works
Medicare's Facility Affiliation Data lists Gunnlaugur P. Nielsen 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.
- Martha's Vineyard Hospital IncOak Bluffs, MA · Critical Access Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 221300
- Massachusetts Eye and Ear Infirmary -Boston, MA · Acute Care Hospital · Emergency services: listed by Medicare · CCN 220075
- Massachusetts General HospitalBoston, MA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 220071
- Nantucket Cottage HospitalNantucket, MA · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 220177
Practice locations
Addresses where Gunnlaugur P. Nielsen is enrolled with Medicare (CMS data updated October 2, 2026).
- 55 Fruit StBoston, MA 02114 (617) 724‑0287
- 81 Highland AveSalem, MA 01970 (978) 741‑1200
Group practices
Medicare enrollment lists Gunnlaugur P. Nielsen as a member of this group (CMS data updated October 2, 2026).
- Massachusetts General Physicians Organization Inc3,558 clinicians in the group
Specialties
- Pathologyprimary
Other pathologists in Boston
Clinicians with the same Medicare primary specialty in Boston, MA — not a recommendation.
Other clinicians in Massachusetts General Physicians Organization Inc
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 1988 (38 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1174592653 |
| 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