Man-Siak Mak, MD
NPI 1609875004 · Gastroenterology Physician · Merced, CA
Enrolled with Medicare as Practitioner - Gastroenterology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Man-Siak Mak, MD is a Gastroenterology Physician provider in Merced, CA (NPI 1609875004).
Provider details
- NPI number
- 1609875004
- Entity type
- Individual
- Primary specialty
- Gastroenterology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- Yes
- License
- A26785 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
20 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
498 Medicare services, 2024 (ranked within specialty)
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 methodology.
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 Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 189 | $92 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 123 | $129 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 | 79 | $169 |
| Biopsy of Esophagus, Stomach, And/Or Upper Small Bowel Using a Flexible Endoscope43239 | 28 | $98 |
| Removal of Polyps Or Growths of Large Bowel Using an Endoscope With Mechanical Snare45385 | 28 | $214 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 4 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Gavilyte-G | 45 | 44 |
| Omeprazole | 32 | 13 |
| Cholestyramine (with Sugar)brand: Cholestyramine | 20 | — |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Peg-3350 and Electrolytes | 15 | 15 |
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.
Practice location
Mailing address
Registry dates
- Enumerated
- 2005-07-18
- Last updated
- 2019-04-17
Frequently asked questions
- What is Man-Siak Mak's NPI number?
- Man-Siak Mak's National Provider Identifier (NPI) is 1609875004, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Man-Siak Mak's specialty?
- Man-Siak Mak is listed in the NPPES registry with a primary specialty of Gastroenterology Physician (Allopathic & Osteopathic Physicians).
- Where is Man-Siak Mak located?
- Man-Siak Mak's practice location on file with NPPES is 3349 G Street Ste. F, Merced, CA 95340.
- What is Man-Siak Mak's phone number?
- The practice phone number listed in the NPPES registry for Man-Siak Mak is (209) 349-8459.
- Does Man-Siak Mak accept Medicare?
- Man-Siak Mak is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Man-Siak Mak's NPI active?
- Yes — Man-Siak Mak's NPI (1609875004) is active in the NPPES registry as of the last update on 2019-04-17.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.