John Caleb Grenn, M.D.
NPI 1225569635 · Internal Medicine Physician · Corpus Christi, TX
Enrolled with Medicare as Practitioner - Pediatric Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
John Caleb Grenn, M.D. is a Internal Medicine Physician provider in Corpus Christi, TX (NPI 1225569635).
Provider details
- NPI number
- 1225569635
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- V9000 (TX)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
9 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
2 documented practice locations
- Medicare service volume (vs. specialty peers)25% of score
484 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 50 Minutes99233 | 265 | $108 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 123 | $72 |
| Initial Hospital Care With Moderate Level of Medical Decision Making, If Using Time, at Least 75 Minutes99223 | 48 | $159 |
| Hospital Discharge Day Management, 30 Minutes Or Less99238 | 48 | $73 |
Typical Medicare-allowed amounts for these services range $72–$159 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 3 distinct drugs on file.
| Drug | Part D claims (2024) |
|---|---|
| Nifedipinebrand: Nifedipine Er | 17 |
| Atorvastatin Calcium | 16 |
| Amlodipine Besylate | 11 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$141 across 6 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Additional practice locations (1)
- 7101 S Padre Island DrCorpus Christi, TX 78412-4913Phone: (877) 832-2652Fax: (877) 454-6896
Registry dates
- Enumerated
- 2017-03-27
- Last updated
- 2025-09-09
- Certified
- 2025-09-09
Frequently asked questions
- What is John Caleb Grenn's NPI number?
- John Caleb Grenn's National Provider Identifier (NPI) is 1225569635, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Caleb Grenn's specialty?
- John Caleb Grenn is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is John Caleb Grenn located?
- John Caleb Grenn's practice location on file with NPPES is 3315 S Alameda St, Corpus Christi, TX 78411-1820.
- What is John Caleb Grenn's phone number?
- The practice phone number listed in the NPPES registry for John Caleb Grenn is (877) 832-2652.
- Does John Caleb Grenn accept Medicare?
- John Caleb Grenn is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is John Caleb Grenn's NPI active?
- Yes — John Caleb Grenn's NPI (1225569635) is active in the NPPES registry as of the last update on 2025-09-09.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.