Clinics and Departments

Laboratory Services

Lab Dept:

Serology

Test Name:

HISTOPLASMA CAPSULATUM ANTIBODY SCREEN

General Information

Lab Order Codes:

HISAB – Screening Test
HAB – Complement Fixation

Synonyms:

Histoplasma Antibody, Serum; Histoplasma Ab; Histoplasma Complement Fixation; Immunodiffusion for Fungi

CPT Codes:

86698 – Antibody; histoplasma
86698 X3 - Antibody; histoplasma (if appropriate)

Test Includes:

Histoplasma capsulatum antbody screen reported as negative, positive or equivocal. If the screen is found to be positive or equivocal, then Histoplasma Antibody by Complement Fixation/Immunodiffusion will be performed at an additional charge.

Logistics

Test Indications:

Useful as an aid in the diagnosis of respiratory disease when Histoplasma infection is suspected.

Histoplasma capsulatum is a soil saprophyte that grows well in soil enriched with bird droppings. The usual disease is self-limited, affects the lungs and is asymptomatic.

Chronic cavitary pulmonary disease, disseminated disease, and meningitis may occur and can be fatal, especially in young children and in immunosuppressed patients.

Lab Testing Sections:

Serology - Sendouts

Referred to:

Mayo Medical Laboratories (Mayo Test# HISTO/83853 and SHSTO)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1 – 2 days, test is set up Sunday - Friday

Special Instructions:

The complement fixation/Immunodiffusion test can be ordered separately, if desired.

Specimen

Specimen Type:

Blood

Container:

Red top tube

Draw Volume:

6 mL (Minimum: 1.5 mL) blood

Processed Volume:

2 mL (Minimum: 0.5 mL) serum

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Centrifuge specimen and remove serum aliquot into a screw-capped round bottom plastic tube. Store and send serum refrigerated. Forward promptly.

Patient Preparation:

None

Sample Rejection:

Specimen collected in incorrect container; specimen other than serum; gross hemolysis; mislabeled or unlabeled specimens

Interpretive

Reference Range:

Screening test: Negative (reported as negative, positive or equivocal)
Negative: Indicates antibodies to histoplasma were not detected.

The absence of antibodies is presumptive evidence that the patient
was not infected with histoplasma. However, the specimen may have been drawn before antibodies were detectable, or the patient may be immunosuppressed. If infection is suspected, another specimen should be drawn 7 to 14 days later and tested.

Equivocal: Specimens with equivocal enzyme immunoassay (EIA) results will be tested by complement fixation and immunodiffusion.

Positive: The presence of antibodies is presumptive evidence that the patient was previously or is currently infected with (or exposed to) histoplasma. These specimens will be tested by complement fixation and immunodiffusion for confirmation.

Complement Fixation/Immunodiffusion test:

Mycelial by complement fixation: negative (positives reported as titer)

Yeast by complement fixation: negative (positives reported as titer)

Antibody by immunodiffusion: negative (positives reported as band present)

Complement fixation (CF) titers ≥1:32 indicate active disease. A rising CF titer is associated with progressive infection.

Positive immunodiffusion test results supplement CF test result.

Patients infected with H. capsulatum demonstrate a serum antibody with a rising titer within 6 weeks of infection. A rising titer is associated with progressive infection. Specific antibody persists for a few weeks to a year, regardless of clinical improvement.

Critical Values:

N/A

Limitations:

The use of this assay has not been established for screening the general population or for monitoring therapy.

The performance of this assay has not been established for ruling out diseases with similar symptoms eg, diseases caused by Mycobacterium tuberculosis, Coccidioides immitis, Aspergillus fumigatus, Blastomyces dermatitidis, Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila or other pathogens.

The performance of this assay has not been established for matrices other than serum.

All results from this and other serologies must be correlated with clinical history, epidemiological data, and other data available to the attending physician in evaluating the patient.

The prevalence of infection will affect the assay's predictive value.

The test can be positive with persons that are not currently infected with histoplasma. Antibodies may be present because of a past infection.

The test can be negative with persons that are currently infected with Histoplasma. Samples obtained very early in the infection may not have detectable antibodies.

Methodology:

Screening test: Enzyme Linked immunosorbent Assay (ELISA)
Reflex test
: Complement Fixation (CF)/Immunodiffusion

References:

Mayo Medical Laboratories (July 2013)



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