Medicare Enrolled
Dr. Mark Walshauser, M.D.
Internal Medicine · O Fallon, IL
Practice pattern: Mixed Practice
— Diverse clinical practice across multiple procedure types
Very High
DATA COVERAGE
Data in 4 of 4 federal sources
Measures public federal data availability — not provider quality
Informational, not a quality rating.
This page presents federal public records about Dr. Walshauser from CMS (NPPES, Open Payments, Medicare Provider Utilization, PECOS). It is not medical advice, an endorsement, or a judgment of clinical quality. Always consult the provider directly and a licensed clinician for medical decisions. Read methodology →
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What this data tells you about Dr. Walshauser
Dr. Mark Walshauser is an internal medicine specialist in O Fallon, IL, with 18 years of NPI registration. Based on federal Medicare data, Dr. Walshauser performed 74,438 Medicare services in 2023. These records do not provide a deduplicated patient total.
Between the years covered by Open Payments, Dr. Walshauser received a total of $24,858 from 80 pharmaceutical and/or device companies across 782 payment records. A record can group multiple payments. These transfers are publicly reported through CMS Open Payments. Disclosure alone does not establish their effect on care. A reliable breakdown by payment category is not available in this snapshot. Patients may wish to discuss these relationships with their provider.
The Data Coverage level for Dr. Walshauser is Very High — reflecting how much public federal data is available about this provider. Patients are encouraged to use this data as one of several factors when choosing a healthcare provider.
✓ 18 years of NPI registration
▲ Top 0% volume in IL
$24,858 industry payments
Medicare Practice Summary — 2023
Medicare Utilization ↗74,438
Medicare services
Top 0% in IL for internal medicine
Not available
Unique patients (not deduplicated)
$6
Avg. Medicare payment
Medicare patients only (65+ / disabled) · How to read this →
Top procedures by volume
Ranked by number of services performed for Medicare patients. Avg. submitted charge is what the provider billed; avg. Medicare payment is what CMS paid.
| Procedure | Volume | Avg. paid | Avg. submitted |
|---|---|---|---|
| Iron infusion (Injectafer) An intravenous injection of ferric carboxymaltose, an iron replacement medication. |
43,500 | $1 | $4 |
| Contrast dye for imaging (iodine-based) A contrast agent containing 300-399 mg/ml of iodine used to enhance imaging studies. It is administered per milliliter to improve the visibility of internal structures. |
14,300 | $0 | $3 |
| Dexamethasone injection (steroid) An injection of dexamethasone sodium phosphate, a corticosteroid medication, administered in a dose of 1 milligram. |
2,687 | $0 | $0 |
| Anti-nausea injection (Aloxi/palonosetron) | 1,520 | $1 | $12 |
| Intravenous injection of additional new drug or substance Administration of an additional new medication or substance directly into a vein. |
1,118 | $12 | $75 |
| Office visit, established patient (30-39 min) A follow-up office visit for an existing patient lasting between 30 and 39 minutes. The visit involves medical evaluation and management of the patient's condition. |
999 | $93 | $200 |
| Comprehensive metabolic blood panel A blood test that measures a group of chemicals, including glucose, electrolytes, and kidney and liver function markers. |
849 | $10 | $73 |
| Anti-nausea injection (ondansetron/Zofran) | 832 | $0 | $0 |
| Blood draw (venipuncture) Insertion of a needle into a vein to collect a blood sample. |
822 | $8 | $24 |
| Manual white blood cell count A laboratory test that involves examining a sample under a microscope to manually count the number of white blood cells present. |
697 | $4 | $27 |
| Complete blood count (CBC), automated An automated laboratory test that measures the levels of red blood cells, white blood cells, and platelets in the blood. |
697 | $6 | $43 |
| Lactate dehydrogenase (LDH) level test A blood test that measures the amount of lactate dehydrogenase, an enzyme found in many body tissues. It helps assess tissue damage or disease. |
578 | $6 | $37 |
| Intravenous chemotherapy infusion, 1 hour or less Administration of chemotherapy medication directly into a vein. The procedure takes one hour or less to complete. |
482 | $98 | $504 |
| Magnesium sulfate injection, per 500 mg An injection of magnesium sulfate administered in 500 mg increments. |
370 | $0 | $1 |
| Immunoglobulin level test A blood test that measures the level of gammaglobulins, which are immune system proteins. |
361 | $9 | $82 |
| Diphenhydramine injection, up to 50 mg An injection of diphenhydramine hydrochloride, an antihistamine medication, administered in a dose of up to 50 milligrams. |
350 | $1 | $3 |
| Office visit, established patient (20-29 min) An office visit for an existing patient lasting between 20 and 29 minutes. The visit involves medical evaluation and management of the patient's condition. |
283 | $61 | $150 |
| Office visit, established patient, complex (40-54 min) An office or outpatient visit for an existing patient lasting between 40 and 54 minutes. This level of service is determined by the total time spent on the date of the encounter. |
277 | $133 | $300 |
| Magnesium level test A blood test to measure the amount of magnesium in your body. This helps check for magnesium deficiency or excess. |
201 | $7 | $56 |
| Intravenous infusion of new drug or substance, 1 hour or less This procedure involves administering a new medication or substance directly into a vein through an existing access site. The infusion is completed within one hour or less. |
199 | $49 | $242 |
| Ferritin level test (iron stores) A blood test that measures the level of ferritin, a protein that stores iron in the body. |
191 | $13 | $127 |
| Drug injection, under skin or into muscle A procedure involving the administration of a medication or substance via injection into the subcutaneous tissue or muscle. |
190 | $11 | $55 |
| Iron level test | 189 | $6 | $55 |
| Iron binding capacity test A blood test that measures the amount of iron in the blood and the blood's ability to bind and transport iron. |
189 | $9 | $76 |
| Additional hour of intravenous chemotherapy This code represents the administration of chemotherapy medication into a vein for each additional hour beyond the initial period. |
185 | $21 | $115 |
| Complete blood count (CBC) with differential An automated laboratory test that measures the levels of red blood cells, white blood cells, and platelets in the blood, including a breakdown of the different types of white blood cells. |
168 | $8 | $47 |
| Vitamin B-12 level test A blood test that measures the amount of vitamin B-12 in your body. |
165 | $15 | $115 |
| Zoledronic acid injection, 1 mg An injection of zoledronic acid administered at a dose of 1 mg. |
153 | $6 | $136 |
| Intravenous drug injection A procedure involving the administration of a medication or substance directly into a vein. |
152 | $28 | $150 |
| Folic acid level test A blood test that measures the amount of folic acid in the serum. |
141 | $14 | $113 |
| Leuprolide acetate (for depot suspension), 7.5 mg | 129 | $134 | $2,153 |
| Carcinoembryonic antigen (CEA) level test A blood test that measures the level of carcinoembryonic antigen (CEA) protein. This test is used to monitor certain types of cancer. |
122 | $19 | $138 |
| Additional hour of intravenous hydration This code represents each additional hour of intravenous fluid administration beyond the initial hour. It is used to bill for extended hydration therapy. |
107 | $10 | $71 |
| Vitamin B-12 injection An injection of vitamin B-12 (cyanocobalamin) with a dose of up to 1000 mcg. |
106 | $1 | $17 |
| CT scan of chest with contrast A computed tomography scan of the chest using a contrast dye to enhance the visibility of internal structures. |
101 | $80 | $1,241 |
| Subcutaneous or intramuscular chemotherapy injection This procedure involves administering anti-cancer hormonal medication through an injection into the tissue under the skin or into a muscle. |
96 | $25 | $117 |
| Automated red blood cell count An automated laboratory test that measures the number of red blood cells in a blood sample. |
93 | $4 | $38 |
| CT scan of abdomen and pelvis with contrast A CT scan that uses dye to create detailed images of the abdomen and pelvis. This imaging test helps doctors examine internal organs and structures in these areas. |
82 | $167 | $1,517 |
| Intravenous hydration infusion, 31-60 minutes Administration of fluids into a vein to maintain hydration. This procedure involves an infusion lasting between 31 and 60 minutes. |
79 | $24 | $167 |
| Normal saline infusion, 1000 cc Administration of 1000 cc of normal saline solution into a vein. This procedure involves the intravenous delivery of a sterile saltwater solution. |
69 | $2 | $12 |
| Immunoglobulin light chain measurement A blood test that measures the levels of immunoglobulin light chains, which are proteins produced by plasma cells. |
50 | $17 | $117 |
| PSA test (prostate cancer screening) | 49 | $18 | $125 |
| Thyroid stimulating hormone (TSH) test A blood test that measures the level of thyroid stimulating hormone to evaluate thyroid function. |
48 | $16 | $119 |
| Intravenous infusion, 1 hour or less Administration of medication or fluid directly into a vein for therapeutic, preventive, or diagnostic purposes. The procedure lasts one hour or less. |
48 | $46 | $214 |
| Irrigation of implanted venous access device This procedure involves flushing an implanted venous access device to clear blockages or maintain patency. It ensures the device remains functional for delivering medications or fluids. |
44 | $18 | $88 |
| Fluorodeoxyglucose f-18 fdg, diagnostic, per study dose, up to 45 millicuries | 42 | $410 | $780 |
| Free thyroxine (T4) test A blood test that measures the level of free thyroxine, a thyroid hormone, in the bloodstream. |
38 | $9 | $87 |
| Hospital follow-up visit, moderate complexity Follow-up hospital visit for an existing patient involving moderate medical decision making. The visit requires at least 35 minutes of time spent on the date of service. |
38 | $60 | $164 |
| Nuclear medicine scan from skull base to mid-thigh with CT A nuclear medicine imaging study covering the area from the base of the skull to the middle of the thighs, performed alongside a CT scan. |
37 | $1,086 | $6,000 |
| New patient office visit (30-44 min) An initial office visit for a new patient lasting between 30 and 44 minutes. This code is used when the total time spent on the date of the encounter falls within this range. |
33 | $70 | $250 |
| New patient office visit (45-59 min) An initial office visit for a new patient lasting between 45 and 59 minutes. This code covers the total time spent by the physician or qualified healthcare professional on the date of the encounter. |
30 | $122 | $350 |
| Additional sequential IV infusion, 1 hour or less This code represents an additional intravenous infusion administered sequentially to a primary infusion. It covers the administration time of one hour or less. |
27 | $22 | $140 |
| Beta-2 microglobulin level test A blood test that measures the level of beta-2 microglobulin, a protein produced by cells in the body. |
21 | $16 | $153 |
| Haptoglobin level test A blood test that measures the amount of haptoglobin, a protein in the serum. It helps evaluate red blood cell breakdown. |
18 | $12 | $125 |
| Initial hospital admission, moderate complexity Initial hospital inpatient or observation care for a new patient involving moderate-level medical decision making, with at least 55 minutes total time on the date of the encounter. |
17 | $98 | $320 |
| Phosphate level test A blood test that measures the amount of phosphate in your body. Phosphate is a mineral that helps keep bones and teeth strong. |
16 | $5 | $38 |
| New patient office visit, complex (60-74 min) | 15 | $174 | $450 |
| Lipid panel (cholesterol and triglycerides) A blood test that measures cholesterol and triglyceride levels. |
13 | $13 | $97 |
| Telephone medical discussion, 5-10 minutes A phone conversation with a physician lasting between 5 and 10 minutes to discuss medical matters. |
13 | $42 | $90 |
| Vitamin D level test A blood test to measure the amount of Vitamin D-3 in your body. |
12 | $29 | $279 |
How to read this data: This reflects Medicare patients only (typically 65+). Payment amounts are what Medicare paid the provider, not your out-of-pocket cost. These counts do not measure clinical quality or years of experience.
59.7% high complexity
29.9% medium
10.4% routine
Industry Payment Transparency
Open Payments through 2024 ↗$24,858
Total received (2018-2024)
Avg $3,551/year across 7 years
Top 3% in IL for internal medicine
A higher payment rank reflects disclosed industry relationships (consulting, research, speaking) common among subspecialists — not wrongdoing.
80
Companies
782
Payment records
Payments are publicly reported; disclosure does not establish legality · Not evidence of wrongdoing · How to interpret →
Payment categories are unavailable while the source breakdown is being rebuilt. Company and year totals do not identify how much belongs to each category.
Payment trend by year
Annual totals from pharmaceutical and medical device companies.
2024
$9,265
2023
$2,313
2022
$2,835
2021
$855
2020
$3,426
2019
$2,996
2018
$3,168
Payments by company (2024)
Regeneron Pharmaceuticals, Inc.
$3,684
BeiGene USA, Inc.
$2,322
AstraZeneca Pharmaceuticals LP
$606
PFIZER INC.
$353
E.R. Squibb & Sons, L.L.C.
$249
Bayer Healthcare Pharmaceuticals Inc.
$234
US Oncology Corporate, Inc.
$218
Novartis Pharmaceuticals Corporation
$180
Cardinal Health 108 LLC
$159
Merck Sharp & Dohme LLC
$152
Astellas Pharma US Inc
$149
Genmab U.S., Inc.
$148
ASD Specialty Healthcare, LLC
$103
ABBVIE INC.
$100
GENZYME CORPORATION
$73
Janssen Biotech, Inc.
$72
Takeda Pharmaceuticals U.S.A., Inc.
$68
Gilead Sciences, Inc.
$54
Rigel Pharmaceuticals, Inc.
$48
Genentech USA, Inc.
$46
Celgene Corporation
$40
SOBI, INC
$38
GlaxoSmithKline, LLC.
$38
Daiichi Sankyo Inc.
$34
Adaptive Biotechnologies Corporation
$22
Incyte Corporation
$19
Pharmacosmos Therapeutics Inc.
$19
Regeneron Healthcare Solutions, Inc.
$18
SERVIER PHARMACEUTICALS LLC
$17
Top 3 companies account for 71.4% of 2024 payments
All-time payments by company (2018-2024) ›
Regeneron Pharmaceuticals, Inc.
$3,833
E.R. Squibb & Sons, L.L.C.
$3,267
BeiGene USA, Inc.
$2,449
Novartis Pharmaceuticals Corporation
$1,706
PFIZER INC.
$1,218
AstraZeneca Pharmaceuticals LP
$1,019
Janssen Biotech, Inc.
$961
GENZYME CORPORATION
$695
Genentech USA, Inc.
$618
Amgen Inc.
$528
Merck Sharp & Dohme Corporation
$502
Takeda Pharmaceuticals U.S.A., Inc.
$467
BeiGene, Ltd.
$450
Celgene Corporation
$424
Merck Sharp & Dohme LLC
$410
Incyte Corporation
$359
Foundation Medicine, Inc.
$339
EMD Serono, Inc.
$300
ASD Specialty Healthcare, LLC
$290
Gilead Sciences, Inc.
$272
Bayer HealthCare Pharmaceuticals Inc.
$270
Bayer Healthcare Pharmaceuticals Inc.
$262
Exelixis Inc.
$259
Astellas Pharma US Inc
$239
ABBVIE INC.
$230
Lilly USA, LLC
$226
US Oncology Corporate, Inc.
$218
Agios Pharmaceuticals, Inc.
$187
Pharmacyclics LLC, An AbbVie Company
$183
Genmab U.S., Inc.
$173
Rigel Pharmaceuticals, Inc.
$161
Cardinal Health 108 LLC
$159
Sirtex Medical Inc
$137
Seattle Genetics, Inc.
$134
Seagen Inc.
$114
Daiichi Sankyo Inc.
$114
Adaptive Biotechnologies Corporation
$108
EISAI INC.
$108
Pharmacyclics LLC, an AbbVie Company
$89
Clovis Oncology, Inc.
$87
JAZZ PHARMACEUTICALS INC.
$70
GlaxoSmithKline, LLC.
$69
ARRAY BIOPHARMA INC
$65
SOBI, INC
$61
Boehringer Ingelheim Pharmaceuticals, Inc.
$57
G1 Therapeutics, Inc.
$57
Eisai Inc.
$57
Kite Pharma, Inc.
$55
SERVIER PHARMACEUTICALS LLC
$53
Janssen Pharmaceuticals, Inc
$45
Karyopharm Therapeutics Inc.
$44
Alexion Pharmaceuticals, Inc.
$42
Regeneron Healthcare Solutions, Inc.
$40
AMAG Pharmaceuticals, Inc.
$39
Deciphera Pharmaceuticals Inc.
$38
AbbVie, Inc.
$35
Lexicon Pharmaceuticals, Inc.
$34
Mylan Institutional Inc.
$32
ADC Therapeutics America, Inc.
$32
Helsinn Therapeutics (U.S.), Inc.
$28
AVEO Pharmaceuticals, Inc.
$24
MorphoSys, US Inc.
$23
TESARO, Inc.
$20
Taiho Oncology, Inc.
$20
Blueprint Medicines Corporation
$20
Pharmacosmos Therapeutics Inc.
$19
Otsuka America Pharmaceutical, Inc.
$18
Novocure Inc.
$17
TerSera Therapeutics LLC
$17
AbbVie Inc.
$17
Servier Pharmaceuticals LLC
$17
Stemline Therapeutics Inc.
$17
Sobi, Inc
$17
Verastem, Inc.
$16
Jazz Pharmaceuticals Inc.
$15
Puma Biotechnology, Inc.
$15
PharmaEssentia USA Corporation
$13
Ipsen Biopharmaceuticals, Inc
$12
Teva Pharmaceuticals USA, Inc.
$11
Heron Therapeutics, Inc.
$11
Top 3 companies account for 38.4% of all-time payments
Associated products mentioned in payments ›
ADAKVEO · ADCETRIS · AFINITOR · AKYNZEO · ALIMTA · ALUNBRIG · AYVAKIT · Abraxane · Alecensa · Avastin · BAVENCIO · BENDEKA · BESREMI · BLENREP · BOSULIF · BRAFTOVI · BRUKINSA · Balversa · Bavencio · Blincyto · CABOMETYX · CALQUENCE · CHANTIX · CINVANTI · COSELA · CYRAMZA · Cabometyx · Columvi · Copiktra · DARZALEX · DOPTELET · Doptelet · ELITEK · EMPLICITI · ENHERTU · ERLEADA · Epkinly · Erleada · FASLODEX · FERAHEME · FOTIVDA · FOUNDATIONONE · FOUNDATIONONE CDX · FRUZAQLA · Fabhalta · Fulphila · GAZYVA · GILOTRIF · IBRANCE · ICLUSIG · IMBRUVICA · IMFINZI · INFLECTRA · INJECTAFER · INLYTA · INREBIC · IRESSA · Imbruvica · Inrebic · JADENU · JAKAFI · JEVTANA · KANJINTI · KEYTRUDA · KISQALI · Kadcyla · Kyprolis · LENVIMA · LIBTAYO · LUMAKRAS · LUTATHERA · LYNPARZA · Lenvima · Lonsurf · Lunsumio · MEKINIST · MONJUVI · MONOFERRIC · NINLARO · Nerlynx · Neulasta · Nplate · Nubeqa · OJJAARA · OPDIVO · OPDUALAG · OXBRYTA · Optune · Orserdu · PADCEV · PEMAZYRE · PIQRAY · PLUVICTO · PROMACTA · Perjeta · Pomalyst · Prolia · QINLOCK · REBLOZYL · RETEVMO · RYBREVANT · Revlimid · Rezlidhia · Rubraca · SAMSCA · SANDOSTATIN · SANDOSTATIN LAR · SARCLISA · SCEMBLIX · SIR-Spheres Microspheres · SPRYCEL · SUTENT · Somatuline Depot · Stivarga · TAFINLAR · TASIGNA · TECENTRIQ · TECVAYLI · TEPMETKO · TIBSOVO · TRUSELTIQ · TUKYSA · Tavalisse · Tecentriq · Tivdak · Trodelvy · ULTOMIRIS · VENCLEXTA · VERZENIO · VOTRIENT · VYXEOS · Venclexta · Vitrakvi · XALKORI · XARELTO · XOSPATA · XPOVIO · XTANDI · Xermelo · Xofigo · Xospata · Xtandi · ZEJULA · ZEPZELCA · ZYTIGA · Zoladex · clonoSEQ
Should you be concerned? Industry payments are disclosed through CMS Open Payments. Disclosure alone does not establish their purpose, legality, or effect on care. What matters is whether a recommended drug or device appears in your doctor's payment records. If so, consider asking your doctor about it. How to interpret this data →
Geographic Context
Internal medicine physicians in nearby ZIP areas
1,143
County median income
$70,178
Nearest hospital to ZIP centroid (approximate)
HSHS ST ELIZABETH'S HOSPITAL
0.0 mi
0.0 mi
Data Sources
| Provider Registry | ✓ NPPES | NPPES snapshot; verify current record |
| Medicare Enrollment | ✓ PECOS | PECOS snapshot |
| Practice Data | ✓ Medicare Util. | Annual (CY lag) |
| Industry Payments | ✓ Open Payments | CY 2024 |
| Disciplinary History | — Not included | N/A |
This provider has data in 4 of 4 available federal datasets, with a Data Coverage level of Very High. This reflects how much public data is available about a provider. How we calculate this →
Summary
Dr. Walshauser is a mixed practice specialist, with above-average Medicare volume (top 0% in IL), with 18 years of NPI registration.
This summary is auto-generated from federal data, describing data availability and patterns. Read our methodology →
Frequently Asked Questions
Is Dr. Walshauser experienced with iron infusion (injectafer)?
Based on Medicare claims data, Dr. Walshauser performed 43,500 iron infusion (injectafer) services. These records cover Medicare fee-for-service activity, including eligible younger beneficiaries; they do not measure total practice volume or clinical quality.
Does Dr. Walshauser receive payments from pharmaceutical companies?
Yes. Dr. Walshauser received a total of $24,858 from 80 companies across 782 payment records. A record can group multiple payments. These transfers are publicly disclosed through CMS Open Payments. Disclosure alone does not establish their legality or effect on care. Patients may wish to ask their doctor about these relationships, especially if a recommended drug or device appears in the payment records.
How do Dr. Walshauser's costs compare to other internal medicine physicians in O Fallon?
Dr. Walshauser's average Medicare payment per service is $6. Note that these figures represent what Medicare pays, not your out-of-pocket cost, which depends on your specific insurance plan and deductible. Procedure-level data above shows both what was submitted and what Medicare paid for each service type.
What does Data Coverage mean?
Data Coverage (currently Very High for Dr. Walshauser) measures how much public federal data is available about a provider. It is not a quality rating. A "Very High" or "High" level means the provider has data across multiple federal sources (NPPES, PECOS, Medicare Utilization, Open Payments), indicating the presence of registry, enrollment, activity or payment records, not verified experience or clinical quality. A "Low" or "Moderate" level may simply mean the provider is newer, does not see Medicare patients, or has not received any industry payments — none of which are inherently negative. Read our full methodology →
Is this data up to date?
Source publication dates and the snapshots loaded on this site can differ. Rebuilding a page does not refresh its source records. Check the Medicare reporting year and the payment interval shown above; consult the linked official sources for newer releases and current registry details. See our data freshness policy →
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About this page
This page combines public CMS records with calculated summaries and explanatory procedure labels. These transformations are not verbatim federal records. Sources: NPPES ↗, Open Payments ↗, Medicare Provider Utilization ↗, and PECOS. Publication is mandated by the Physician Payments Sunshine Act (§6002 ACA, 42 U.S.C. §1320a-7h) and the Freedom of Information Act.
This page is not medical advice, an endorsement, a recommendation, or a quality rating. Data Coverage reflects data completeness — how much federal information exists for this provider — not clinical performance, patient outcomes, or quality of care. Always verify information directly with the provider and consult a licensed clinician before making medical decisions.
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