Summary & Overview
CPT 86641: Cryptococcus Antibody Immunoassay, Blood or CSF
CPT code 86641 represents a laboratory immunoassay that detects antibodies to the fungus Cryptococcus in patient blood or cerebrospinal fluid (CSF). This diagnostic test supports evaluation for cryptococcal infection, including cryptococcal meningitis, and is relevant across inpatient and outpatient laboratory settings. Nationally, accurate coding and utilization of this assay affect infectious disease diagnostics, laboratory workflows, and payer coverage for fungal disease testing.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication provides a concise reference for clinical and billing teams on the clinical purpose of the service, typical sites of service, and the payer landscape relevant to laboratory-based fungal antibody testing. Readers will find benchmarks and contextual information about how this CPT code is used in clinical workflows, common modifiers associated with laboratory claims (listed separately), and guidance on documentation elements that typically accompany such testing. The content is designed for a national audience of laboratory managers, billing professionals, and clinical leaders seeking a clear summary of the code's clinical role, typical settings, and payer considerations. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 86641 describes an immunoassay performed by a laboratory analyst to detect antibodies to the fungus Cryptococcus in patient blood or cerebrospinal fluid (CSF). This test identifies host immune response to Cryptococcus species and is used in the diagnostic evaluation of suspected cryptococcal infection, including meningitis when CSF is tested.
Service type: Laboratory diagnostic immunoassay
Typical site of service: Clinical laboratory or hospital laboratory; specimen types include blood (serum/plasma) and cerebrospinal fluid (CSF).
Clinical & Coding Specifications
Clinical Context
A patient presents to the emergency department or infectious disease clinic with subacute headache, fever, neck stiffness, altered mental status, or signs of systemic fungal infection. The clinician performs a lumbar puncture to obtain cerebrospinal fluid (CSF) when cryptococcal meningitis is suspected, or orders serum testing when disseminated cryptococcosis is a concern. The laboratory performs an immunoassay to detect antibodies to Cryptococcus in blood or CSF, reported under CPT 86641. Typical workflow: clinician documents clinical suspicion (for example, immunocompromised status such as HIV/AIDS, transplant recipient, or prolonged corticosteroid use), obtains appropriate specimen (serum or CSF) with proper labeling and requisition containing relevant ICD-10 diagnosis, transports specimen to the microbiology or serology lab, and the lab analyst runs the cryptococcal antibody immunoassay. Results are reviewed by the laboratory director or designee and communicated to the ordering provider for correlation with antigen testing, culture, and clinical findings. Typical sites of service include the hospital inpatient unit, emergency department, outpatient infectious disease clinic, and clinical laboratory services.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | No modifier applicable (placeholder) | Rarely used; not typically appended — included in payer lists as default. |