Quick answers
- Does John Reyes-Castano accept Medicare assignment?
- Yes. Medicare's clinician data says John Reyes-Castano 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 John Reyes-Castano see?
- In 2024, CMS data shows 15 Original Medicare patients and 35 services for John Reyes-Castano. This counts Original Medicare only and measures volume, not quality.
- What is John Reyes-Castano's NPI number?
- 1073770145. 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 John Reyes-Castano, 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 | 15 |
|---|---|
| Services billed to Medicare | 35 |
| Different services or procedures | 11 |
| Participating Medicare provider | Yes |
| Average age of these patients | 68 |
Practice locations
Addresses where John Reyes-Castano is enrolled with Medicare (CMS data updated October 2, 2026).
- 1221 Mercantile LnLargo, MD 20774 (301) 618‑5700
- 13285 Minnieville RdWoodbridge, VA 22192 (703) 986‑2400
- 8008 Westpark DrMc Lean, VA 22102 (703) 287‑6400
Group practices
Medicare enrollment lists John Reyes-Castano as a member of this group (CMS data updated October 2, 2026).
- Kaiser Foundation Health Plan of the Mid Atlantic States, Inc1,899 clinicians in the group
Specialties
- Endocrinologyprimary
- Internal Medicinealso
Other endocrinologists in Largo
Clinicians with the same Medicare primary specialty in Largo, MD — not a recommendation.
Other clinicians in Kaiser Foundation Health Plan of the Mid Atlantic States, Inc
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2001 (25 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) | 1073770145 |
| 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