Quick answers
- Does Mark H. Gardenswartz accept Medicare assignment?
- Yes. Medicare's clinician data says Mark H. Gardenswartz 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 Mark H. Gardenswartz see?
- In 2024, CMS data shows 438 Original Medicare patients and 3,774 services for Mark H. Gardenswartz. This counts Original Medicare only and measures volume, not quality.
- What is Mark H. Gardenswartz's NPI number?
- 1326063215. 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 Mark H. Gardenswartz, 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 | 438 |
|---|---|
| Services billed to Medicare | 3,774 |
| Different services or procedures | 24 |
| Participating Medicare provider | Yes |
| Average age of these patients | 77 |
Most frequent services
- Visit complexity inherent to evaluation and management associated with medical care services that serve as the continuing focal point for all needed health care services and/or with medical care services that are part of ongoing care related to a patient's (G2211)997 services
- Insertion of needle into vein for collection of blood sample (36415)901 services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)879 services
- Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes (99233)356 services
- Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more (99215)120 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%
- Chronic kidney disease62%
- Arthritis56%
- Ischemic heart disease54%
- Diabetes48%
Hospitals where Mark H. Gardenswartz works
Medicare's Facility Affiliation Data lists Mark H. Gardenswartz 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.
- Lenox Hill HospitalNew York, NY · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 330119
- Phelps HospitalSleepy Hollow, NY · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 330261
Practice locations
Addresses where Mark H. Gardenswartz is enrolled with Medicare (CMS data updated October 2, 2026). The first 5 of 10; the Medicare profile lists all.
- 100 E 77th StNew York, NY 10075
- 110 E 58th StNew York, NY 10022
- 111 E 77th StNew York, NY 10075 (212) 434‑3966
- 1111 Marcus AveNew Hyde Park, NY 11042
- 16 Sumner PlBrooklyn, NY 11206
Group practices
Medicare enrollment lists Mark H. Gardenswartz as a member of these groups (CMS data updated October 2, 2026).
- North Shore-Lij Medical PC6,440 clinicians in the group
- Ahava Medical and Rehabilitation Center, LLC152 clinicians in the group
Specialties
- Nephrologyprimary
- Internal Medicinealso
Other nephrologists in New York
Clinicians with the same Medicare primary specialty in New York, NY — not a recommendation.
Other clinicians in North Shore-Lij Medical PC
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Colorado School Of Medicine, Denver |
| Graduation year | 1975 (51 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1326063215 |
| 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