James Clark, M.D.
NPI 1588640650 · Gastroenterology Physician · Downers Grove, IL
Enrolled with Medicare as Practitioner - Gastroenterology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
James Clark, M.D. is a Gastroenterology Physician provider in Downers Grove, IL (NPI 1588640650).
Provider details
- NPI number
- 1588640650
- Entity type
- Individual
- Primary specialty
- Gastroenterology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
20 yrs in NPPES registry
- Profile completeness25% of score
83% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
898 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) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 190 | $130 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 161 | $80 |
| Biopsy of Esophagus, Stomach, And/Or Upper Small Bowel Using a Flexible Endoscope43239 | 95 | $97 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 | 85 | $173 |
| Removal of Polyps Or Growths of Large Bowel Using an Endoscope With Mechanical Snare45385 | 70 | $256 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 13 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Pantoprazole Sodium | 299 | 107 |
| Omeprazole | 100 | 35 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Gavilyte-G | 75 | 75 |
| Mesalamine | 60 | 17 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Peg-3350 and Electrolytes | 44 | 43 |
| Peg3350/Sod Sul/Nacl/Kcl/Asb/Cbrand: Plenvu | 42 | 42 |
| Sodium, Potassium,mag Sulfates |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$1,316 across 65 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
Registry dates
- Enumerated
- 2005-12-20
- Last updated
- 2007-07-08
Frequently asked questions
- What is James Clark's NPI number?
- James Clark's National Provider Identifier (NPI) is 1588640650, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is James Clark's specialty?
- James Clark is listed in the NPPES registry with a primary specialty of Gastroenterology Physician (Allopathic & Osteopathic Physicians).
- Where is James Clark located?
- James Clark's practice location on file with NPPES is 3825 Highland Ave, Downers Grove, IL 60515-1552.
- What is James Clark's phone number?
- The practice phone number listed in the NPPES registry for James Clark is (630) 434-9312.
- Does James Clark accept Medicare?
- James Clark is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is James Clark's NPI active?
- Yes — James Clark's NPI (1588640650) is active in the NPPES registry as of the last update on 2007-07-08.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.