Recently Updated NPI Information — some details in this NPI profile have been updated in the NPI registry within the last 60 days.

MS. PIA GABRIELLE ISIDRO ALFONSO M.D.
NPI 1356035737
Internal Medicine in Fontana, CA

Q: What is Pia Gabrielle Alfonso's NPI number?

The NPI number for Pia Gabrielle Alfonso is 1356035737. It was assigned to this individual provider in the NPPES registry on June 7, 2023.

Q: What is Pia Gabrielle Alfonso's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Active since June 07, 2023PECOS Enrolled

9961 SIERRA AVE, FONTANA, CA 92335(888) 750-0036 Get Directions Write a Review

NPPES record last updated: September 24, 2026. Verified against the NPPES registry weekly; last sync: October 11, 2026.

Record update history: Sep 24, 2026, Jun 6, 2024, Dec 7, 2023 and 1 more (4 updates tracked since 2023).

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About Ms. Pia Gabrielle Isidro Alfonso M.d. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

MS. PIA GABRIELLE ISIDRO ALFONSO M.D. (NPI 1356035737) is an individual internal medicine provider in Fontana, California, licensed in California (A209254) and active in the NPI registry since June 2023. She is enrolled in Medicare PECOS and maintains a secondary practice location in Boston.

NPPES Registry Identity

NPI1356035737

Entity TypeIndividualFemale

Primary Taxonomy207R00000X

Provider Legal NameMS. PIA GABRIELLE ISIDRO ALFONSOCredential: M.D.

Location Address9961 SIERRA AVEFontana, CA 92335-6720

Mailing Address9961 Sierra AveFontana, CA 92335-6720 · (888) 750-0036

Phone(888) 750-0036

Sole ProprietorNo

Enumeration DateJune 7, 2023

Last NPPES UpdateSeptember 24, 20264 updates tracked since enumeration

NPPES CertifiedSeptember 24, 2026

✔ NPI 1356035737 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses 2

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians

Taxonomy Code207R00000X

Licenses✔ Licensed in CA · A209254✔ Licensed in MA · 3014865

Definition

A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.

Also ListedStudent in an Organized Health Care Education/Training ProgramTaxonomy 390200000X

9961 SIERRA AVE, Fontana, CA 92335

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Secondary Practice Location 1

Location 1736 Cambridge StreetBoston, MA 02135 · Phone (617) 789-3000 · Fax (617) 789-2438

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, and ordering and referring status from the CMS PECOS system.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Ms. Pia Gabrielle Isidro Alfonso M.d. is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 92335 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient

$136.04 typical visit price

range $59.60 – $179.42

Typical copayment $34.01 (range $14.90 – $44.85)

Most-billed visit code 99204

Established Patient

$104.64 typical visit price

range $19.37 – $146.42

Typical copayment $26.16 (range $4.84 – $36.60)

Most-billed visit code 99214

Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Other Providers at the Same Location NPPES 20

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

SHEILA ANN VANALLEN PT

Physical Therapist

9961 SIERRA AVE, BUILDING 3A
FONTANA, CA 92335

San Bernardino County (909) 427-7727

MR. JAMES DAVID KILLEEN III M.D.

Pediatrics

9961 SIERRA AVE, KAISER PERMANENTE FONTANA - PEDIATRICS
FONTANA, CA 92335

San Bernardino County (909) 427-6960

MR. DHIRESH N PATEL RPH

Pharmacist