Dr. Keith Marcus, MD
Internal Medicine (Internal Medicine Physician)
1 Atkinson Dr
Ludington, MI 49431
Who else practices at this address →
Mason County is a federal mental health shortage area. About shortage areas
- Medicare participating
At a glance
- Medical school
- University of Iowa, Rj & L Carver College of Medicine (1985)
- Years since graduation
- 41
- In the NPI registry since
- 2006
- Medicare patients seen, 2024
- 110
The NPI date is when this clinician registered for a National Provider Identifier, the billing number used on health claims. It is not a license, graduation or board-certification date. NPIs were first issued in May 2005 and became required on claims in 2007–2008, so an early date usually means the clinician was already in practice before then. What an NPI is
Education and training
- 1985Medical school: University of Iowa, Rj & L Carver College of Medicine
- 2006Registered with an NPI (national billing number; not a license date) — NPIs began in 2005, so practice likely started earlier
Undergraduate school, residency, fellowship, licensing exams and board certification aren’t in public federal data. Board certification can be confirmed with the certifying board (ABMS member boards for MDs, AOA boards for DOs).
Specialties and state licenses
-
Internal Medicine Physician primary
MI license 4301050045
As reported to the NPI registry. To confirm a license is current, check the state medical board.
Where they work
Hospitals
- Corewell Health Ludington Hospital Ludington, MI
Medical groups
- Spectrum Health Primary Care PArtners (2,294 clinicians)
Hospitals this clinician lists with Medicare, and groups they bill Medicare through (Care Compare). Affiliation doesn’t mean they see patients at every location.
Medicare patients and services
- Medicare patients, 2024
- 110
- Services billed
- 245
- Patients’ average age
- 76
| Service | Times | Patients |
|---|---|---|
| Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes | 139 | 71 |
| Hospital discharge day management, more than 30 minutes | 69 | 63 |
| Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes | 68 | 44 |
| Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes | 35 | 33 |
| Critical care, first 30-74 minutes | 30 | 13 |
Medicare fee-for-service only. CMS leaves out services billed for fewer than 11 patients. These figures describe a practice’s Medicare work; they aren’t a measure of quality.
Medicare prescriptions
| Drug | Prescriptions |
|---|---|
| Pantoprazole Sodium Other prescribers in Ludington, MI | 23 |
| Omeprazole Other prescribers in Ludington, MI | 17 |
| Potassium Chloride Other prescribers in Ludington, MI | 15 |
| Cefuroxime (cefuroxime axetil) Other prescribers in Ludington, MI | 14 |
| Prednisone Other prescribers in Ludington, MI | 14 |
| Furosemide Other prescribers in Ludington, MI | 13 |
| Atorvastatin Calcium Other prescribers in Ludington, MI | 11 |
| Metoprolol Succinate Other prescribers in Ludington, MI | 11 |
Prescriptions filled under Medicare Part D, including refills. CMS leaves out drugs prescribed fewer than 11 times.
Payments from drug and device companies
In 2025, 3 companies reported 12 payments worth $563 in total to this clinician.
| Galderma Laboratories, L.P. | $317 |
|---|---|
| AbbVie Inc. | $218 |
| Merz North America, Inc. | $28.24 |
| Food and Beverage | $563 |
|---|
From CMS Open Payments. A payment is not evidence of wrongdoing; many are for consulting, teaching or meals. Clinicians can review and dispute their records with CMS.
Industry-funded research
Named as a principal investigator on 5 industry-funded studies in 2025, from 1 companies. The companies reported $575,410 in research payments for these studies, mostly to the institutions running them.
- A Study to Assess the Adverse Events of Intramuscular Injections of AGN-151586 and OnabotulinumtoxinA in Adult Participants for the Change of Glabellar Lines (GL)
AbbVie Inc. · Completed · NCT06834789 - A Study to Evaluate Patient Satisfaction With the Overall Face and Neck Appearance After Combined Treatment of OnabotulinumtoxinA, JUVÉDERM® Products, KYBELLA, CoolSculpting Elite and SkinMedica Products
AbbVie Inc. · Completed · NCT06783621 - M24-704 - A Study to Evaluate Patient Satisfaction With the Overall Face and Neck Appearance After Combined Treatment of OnabotulinumtoxinA, JUVEDERM Products, KYBELLA, CoolSculpting Elite and SkinMedica Products (US …
AbbVie Inc. - A Study to Assess the Adverse Events of Intramuscular Injections of AGN-151586 and OnabotulinumtoxinA in Adult Participants for the Change of Glabellar Lines (GL)
AbbVie Inc. - A Study to Evaluate Patient Satisfaction With the Overall Face and Neck Appearance After Combined Treatment of OnabotulinumtoxinA, JUVEDERM Products, KYBELLA, CoolSculpting Elite and SkinMedica Products (US Harmony)
AbbVie Inc.
From CMS Open Payments research payments, where companies name up to five principal investigators per payment. Research payments usually go to hospitals, universities and research sites, not to the investigator personally. A payment is not evidence of wrongdoing.