CPT 87328: Cryptosporidium Antigen Immunoassay

CPT code 87328 denotes an immunoassay laboratory test for detection of Cryptosporidium antigens, a clinically important diagnostic for patients with suspected parasitic gastrointestinal infection. Nationally, this code supports surveillance and targeted treatment decisions, and it factors into lab reimbursement and public health reporting frameworks. Key payers commonly involved in coverage and reimbursement of this test include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. This publication provides readers with a concise overview of the code's clinical application, typical sites of service, and the payer landscape. It summarizes what stakeholders need to know about billing and coding context, common service settings, and how this test fits into diagnostic workflows for infectious diarrhea. The analysis includes benchmark-level discussion of reimbursement trends and payer coverage considerations where available, as well as any recent policy updates affecting laboratory claims processing. Clinical context is provided to clarify when the test is typically ordered and how results inform patient management. Data not available in the input is noted explicitly where relevant.

Billing Code Overview

CPT code 87328 describes a laboratory immunoassay performed to detect Cryptosporidium antigens. The procedure uses an immunoassay technique (for example, enzyme immunoassay) to identify protozoan antigens in clinical specimens.

Service type: Laboratory diagnostic test, infectious disease antigen detection

Typical site of service: Clinical laboratory or hospital laboratory

Clinical Context

A symptomatic adult or pediatric patient presents to an outpatient clinic, emergency department, or inpatient unit with acute watery diarrhea, abdominal cramping, and possible low-grade fever after recent travel, daycare exposure, or known contaminated water exposure. The clinician orders stool testing to evaluate infectious causes. A stool specimen is collected and sent to the clinical laboratory. A medical laboratory scientist or technologist performs an immunoassay (for example, enzyme immunoassay, EIA) to detect Cryptosporidium antigen in the stool. Results are reported to the ordering clinician for treatment decisions and infection control. Typical sites of service include hospital laboratories, independent clinical labs, outpatient clinics with on-site lab services, and public health laboratories. Turnaround time is usually hours to 1–2 days depending on lab workflow and batching practices.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the professional interpretation component if separated from technical services
`TC`	Technical component	Use when billing only the technical component (laboratory processing and equipment)

Taxonomy Code	Specialty	Notes
174400000X	Emergency Medicine	ED clinicians frequently order stool infectious workups
208D00000X	Family Medicine	Primary care physicians ordering outpatient stool testing
207Q00000X	Infectious Disease	Specialists interpreting complex infectious diarrhea cases
1223P0001X	Clinical Laboratory Scientist/Technologist	Personnel who perform the `87328` immunoassay testing
207L00000X	Gastroenterology	Gastroenterologists managing persistent or severe diarrheal illness

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`A09`	Infectious gastroenteritis and colitis, unspecified	Common presenting diagnosis for acute diarrheal illness prompting stool testing including Cryptosporidium antigen
`A04.7`	Enterocolitis due to Campylobacter	Bacterial cause of diarrhea often considered in differential diagnosis alongside parasitic testing
`A02.0`	Salmonella enteritis	Bacterial enteritis included in initial stool workup alongside parasitic antigen testing
`A07.2`	Enteritis due to Giardia lamblia	Another protozoal cause of diarrhea; testing for multiple parasites may be ordered together
`K52.9`	Noninfective gastroenteritis and colitis, unspecified	Used when clinical features overlap and infectious etiology is being evaluated
`B00.9`	Herpesviral infection, unspecified	Data not directly related but sometimes present in immunocompromised patients with systemic infection
`B20`	Human immunodeficiency virus [HIV] disease	Immunocompromised patients with HIV are at increased risk for severe cryptosporidiosis

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`87045`	Culture, bacterial; stool, routine, with isolation and presumptive identification of each organism	Bacterial stool culture often ordered alongside parasitic antigen testing when bacterial enteropathogens are suspected
`87209`	Wet mount for infectious agents, direct microscopic; feces, any number of organisms (eg, ova and parasites)	Microscopic ova and parasite exam frequently performed in parallel with antigen testing for parasitic causes of diarrhea
`87486`	Infectious agent detection by nucleic acid (DNA or RNA); protozoa, multiple pathogens, amplified probe technique	Molecular multiplex panels may be used instead of or in addition to `87328` for broader pathogen detection
`87086`	Culture, bacterial; urine, quantitative colony count (not directly related)`	Data not available in the input.
`G0472`	Infectious disease testing, non-specific (example code for CMS programs)	Used in some settings for reporting bundled laboratory infectious disease testing

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Summary & Overview