HISTOPLASMA ANTIBODY IMMUNODIFFUSION

Test Code

321
CPT Code

86698
Clinical Significance
- The histoplasma antibody immunodiffusion test is used for the in vitro determination of precipitating antibodies to Histoplasma sp. It is also used as an aid in the diagnosis of Histoplasmosis.
- This test detects the presence of two significant precipitin bands. Presence of both the H and the M band indicates active histoplasmosis. The presence of the M band alone indicates early or chronic disease. The M band may also be present following a recent histoplasmin skin test.
Methodology

Fungal Immunodiffusion
Limitations
The result is not intended to be used as the sole means for clinical diagnosis or patient management decisions.
- Negative serologic tests may be observed among culturally demonstrable cases, which limits the predictive value of a negative test.
- Negative serologic results obtained during the first month may warrant repeat testing.
- Falsely negative results may be obtained when testing immunocompromised patients.
- Test results cannot be used solely, to distinguish between active infection and prior exposure.
Specimen Collection

Serum: Collect serum specimens in serum separator or red top tube. Allow blood to clot for 30 minutes, then centrifuge. Pipette serum into a plastic screw cap vial.
Minimum Specimen Requirements

Serum: 0.25 mL per antibody
Specimen Stability
- Refrigerated: 14 days
- Frozen: 6 months
Specimen Rejection

Any specimen types other than serum.
Transport Temperature

Refrigerated/Frozen
Shipping

Ship on dry ice to arrive Monday‐Friday using a next day delivery service. Frozen ice packs may be substituted if sample is shipped the day of collection.
Turnaround Time

Testing performed Tuesdays and Fridays.

Serum: TAT 72 hours from setup
Reference Range
- Antibody not detected
- Will report H and M bands
Interpretative Information
- Negative: Antibody not detected
- Positive: Antibody detected