Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Spencer John Mares, FNP-C, AGACNP-BC

Individual provider Family Nurse Practitioner · NPI 1437667490

Spencer John Mares, FNP-C, AGACNP-BC is a Nurse Practitioner in Lake Saint Louis, Missouri. Qualified in 2017, 9 years ago. Practices with Sound Physicians of Illinois LLC, a 195-clinician group and accepts Medicare assignment. Licensed in Illinois and Missouri.

Years since qualifying
9
Licensed in
IL, MO
In the registry since
2018
Specialties on file
3
What do these letters mean?
FNP-C — Family Nurse Practitioner, Certified
A family nurse practitioner certified by the AANP.

See every abbreviation used in this directory →

Practice location Address checks out

100 Medical Plz
Lake Saint Louis, MO 63367-1366
Phone: (636) 625-5200
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Acute Care Nurse Practitioner (primary) Taxonomy 363LA2100X · Licence 2023006109 (MO)
Family Nurse Practitioner Taxonomy 363LF0000X · Licence 2018001739 (MO)
Family Nurse Practitioner Taxonomy 363LF0000X · Licence 277.000663 (IL)

Record details

NPI number1437667490
Entity typeIndividual (Type 1)
GenderMale
Credentials FNP-C , AGACNP-BC
Sole proprietorNo
NPI enumeratedJanuary 11, 2018
Last updated in NPPESMarch 10, 2023
Certification dateMarch 10, 2023

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyNURSE PRACTITIONER
Medical schoolOTHER
Graduated 2017 (9 years in practice)
Group practice Sound Physicians Of Illinois Llc — 195 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations3 on file with Medicare

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients251
Services billed 363 a service is one billed item, such as a visit, a test or a procedure
Average patient age77

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Sound Physicians of Illinois LLC

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 195 clinicians in the practice; 12 are shown here.

Other providers in Lake Saint Louis