Quantiferon Gold TB blood test in NYC and Long Island

QuantiFERON and IGRA TB testing

QuantiFERON-TB Gold Plus is an interferon-gamma release assay, or IGRA, that checks an immune response to tuberculosis antigens in a blood sample. It is a different test from PPD. One collection visit can provide the sample, while interpretation and follow-up may need another contact.

How quantiFERON and IGRA TB testing works

An IGRA is not affected by BCG vaccination in the way a skin test can be. The result can be positive, negative or indeterminate. An indeterminate result does not provide a useful answer and may require another test. Recent exposure or immune suppression can produce a negative result despite infection.

Eligibility: QuantiFERON and IGRA TB testing

An IGRA may be useful for people with BCG vaccination or those unlikely to return for a skin-test reading. Age and the requesting program's rules matter. CDC generally recommends a skin test for children younger than five while noting that some experts use blood tests. A clinician should choose the method for the child.

What to expect: QuantiFERON and IGRA TB testing

Review prior results, treatment, exposure and symptoms before testing. The specimen has time-sensitive processing requirements. A positive result leads to an evaluation for TB disease. The blood test alone cannot distinguish latent infection from active TB or determine contagiousness.

Preparing for your appointment

Bring the school or employer requirement and previous TB records. Fasting is generally not the main preparation, but follow the collection team's instructions. Mention recent live-virus vaccination and a new exposure. Do not order repeat testing solely to replace a documented prior positive.

Risks and when to seek help

Do not assume a positive result is caused by BCG. Do not assume a negative test rules out TB in a symptomatic person. Contact the clinician about persistent cough, fever, night sweats or weight loss and disclose the concern before arrival.

Follow-up and treatment review

If recent exposure is suspected, the clinician may plan repeat testing after the immune response has had time to develop. Positive and indeterminate results need different next steps. Confirm who will complete the evaluation and return the report to the requesting program.

Appointments, costs and coverage

Confirm the current IGRA assay, collection schedule, laboratory network and expected reporting interval. Same-day collection does not promise same-day results or immediate school or employment clearance.

Medical sources

• CDC: TB blood tests
• CDC TB testing and diagnosis
• CDC Clinical Testing Guidance: Tuberculin Skin Test