Quick answers
- Does Karl K. Gruber accept Medicare assignment?
- Yes. Medicare's clinician data says Karl K. Gruber 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 Karl K. Gruber see?
- In 2024, CMS data shows 428 Original Medicare patients and 1,012 services for Karl K. Gruber. This counts Original Medicare only and measures volume, not quality.
- What is Karl K. Gruber's NPI number?
- 1619944758. 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 Karl K. Gruber, 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 | 428 |
|---|---|
| Services billed to Medicare | 1,012 |
| Different services or procedures | 16 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- Pathology examination of tissue using a microscope, intermediate complexity (88305)647 services
- Special stained specimen slides to identify organisms including interpretation and report (88312)99 services
- Pathology examination of tissue using a microscope, moderately low complexity (88304)46 services
- Evaluation of fine needle aspirate with interpretation and report (88173)29 services
- Cell examination of specimen, selective cellular enhancement technique (88112)26 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 pressure74%
- High cholesterol59%
- Diabetes37%
- Arthritis34%
- Cancer (breast, colorectal, lung, prostate, endometrial or leukemia/lymphoma)20%
- Chronic kidney disease19%
Hospitals where Karl K. Gruber works
Medicare's Facility Affiliation Data lists Karl K. Gruber 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.
- Gov Juan F Luis Hospital & Medical CenterSt Croix, VI · Acute Care Hospital · Medicare rating: 1 of 5 stars · Emergency services: listed by Medicare · CCN 480002
Practice locations
Addresses where Karl K. Gruber is enrolled with Medicare (CMS data updated October 2, 2026).
- 4007 Estate Diamond RubySt Croix, VI 00820 (340) 778‑6377
Specialties
- Pathologyprimary
Clinician information
| Credential | MD |
|---|---|
| Medical school | Medical University Of South Carolina College Of Medicine |
| Graduation year | 1992 (34 years since medical school) |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1619944758 |
| 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