Doctor profile · Federal record
Dr. Mark Grenquist, DO
Internal Medicine Physician (CMS: Hospitalist) · Hospitalist Physician · Chelsea, MI
- NPI 1942300454
- Accepts Medicare
- 25 yrs in practice
- Male
- Group practice
- No sanctions
Practice & contact
- Primary practice
-
775 S Main St
Chelsea, MI 481181383
(734) 593-6000 - Mailing address
-
24 Frank Lloyd Wright Dr, Po Box 0446 - Lobby J
Ann Arbor, MI 481059484
Credentials & registration
- NPI registered
- September 2006 — 20 yrs on file
- Profile last updated
- September 6, 2016
- Year of graduation
- 2001 — 25 yrs since
- Specialty taxonomy
- 207R00000X — NUCC code
- State license (1)
- Michigan #5101014936
- Medicaid (2)
- MI #1942300454 · MI #4631106
Federal sanctions & exclusions
No sanctions, exclusions or revocations on file
Checked against OIG LEIE on NPI 1942300454. Last verified May 11, 2026.Medicare procedures · 2023
Top services delivered
Total services
318
Distinct HCPCS
5
Medicare allowed
$32,519
| HCPCS | Description | Services | Patients | Avg allowed | |
|---|---|---|---|---|---|
99232 |
Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes | 159 | 73 | $76 | |
99239 |
Hospital discharge day management, more than 30 minutes | 63 | 60 | $110 | |
99222 |
Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes | 34 | 34 | $131 | |
99223 |
Initial hospital care with moderate level of medical decision making, if using time, at least 75 minutes | 34 | 33 | $168 | |
99233 |
Subsequent hospital care with moderate levelof medical decision making, if using time, at least 50 minutes | 28 | 20 | $115 |
In context: peer comparison
Among 4 peers in this city , average services per provider: 81. This provider delivers 3.9× the peer median.Medicare Part D · 2023
Top prescriptions
Total claims
11
Patients
11
Total drug cost
$48
| Drug | Type | Claims | Patients | Total cost |
|---|---|---|---|---|
| Levofloxacin | Generic | 11 | 11 | $48 |
Frequently asked questions
What is Dr. Mark Grenquist's medical specialty?
Dr. Mark Grenquist practices Internal Medicine Physician in Chelsea, MI.
Where does Dr. Mark Grenquist practice?
Dr. Mark Grenquist practices at 775 S Main St, Chelsea, MI 481181383. Office phone: 7345936000.
What is Dr. Mark Grenquist's NPI?
Dr. Mark Grenquist's National Provider Identifier (NPI) is 1942300454, issued by NPPES.
Does Dr. Mark Grenquist accept Medicare assignment?
Yes. Dr. Mark Grenquist accepts Medicare assignment, meaning Medicare-allowed amounts are accepted as full payment for covered services.
What procedures does Dr. Mark Grenquist commonly perform?
Top Medicare-reported procedures in 2023: Subsequent hospital care with moderate levelof medical decision making (HCPCS 99232); Hospital discharge day management (HCPCS 99239); Initial hospital care with straightforward or low-level medical decision making (HCPCS 99222). Source: CMS Medicare Physician & Other Practitioners file.