Tuberculosis (TB) is a serious bacterial infection caused by Mycobacterium tuberculosis, which primarily affects the lungs but can target other organs. Screening is frequently required for many professional and personal situations, even though not everyone exposed develops active disease. Urgent care facilities commonly offer this testing, providing a convenient option for individuals who need rapid documentation for health screening or administrative purposes, such as starting a new job or academic program.
Which TB Tests Are Available at Urgent Care
Urgent care centers most frequently provide the Tuberculin Skin Test (TST), also known as the Purified Protein Derivative (PPD) test, as the primary method for TB screening. This test involves injecting a small amount of tuberculin protein into the skin of the inner forearm using the Mantoux technique. The injection creates a small, pale bump, or wheal, indicating successful administration. The PPD test detects the presence of an immune response, suggesting the person has been exposed to the TB bacteria.
The skin test is a two-part process requiring the patient to return to the facility to complete the assessment. A trained professional must physically examine and measure the test site between 48 and 72 hours after the initial injection. If a patient does not return within this specific window, the test becomes invalid and must be repeated.
Some urgent care facilities also offer Interferon-Gamma Release Assays (IGRAs), which are blood tests that provide an alternative to the TST. These tests measure the immune system’s release of interferon-gamma in response to specific TB antigens. IGRAs, such as QuantiFERON-TB Gold Plus, are advantageous because they require only a single visit and are not affected by prior vaccination with the Bacillus Calmette-Guérin (BCG) vaccine.
While the TST is generally less expensive and widely available, the IGRA blood test is preferred for people who have received the BCG vaccine or those unable to return for the required two-day follow-up appointment. The choice between the skin test and the blood test often depends on the urgent care center’s resources and the patient’s individual risk factors.
Common Reasons for Needing a TB Test
Most people seek TB testing because a regulatory body requires screening, not because they are symptomatic. A common reason is pre-employment screening, particularly for positions in high-risk environments such as healthcare, long-term care facilities, and correctional settings. Educational and childcare institutions often mandate TB testing for new staff and sometimes for students.
Academic enrollment, especially for students entering medical or allied health programs, frequently includes a TB test as a prerequisite for clinical rotations. International travel or immigration processes, including applications for permanent residency, also require documented TB screening. These requirements ensure individuals entering a new country or who will be in close contact with vulnerable populations are screened.
Individuals who have recently been in close, prolonged contact with someone diagnosed with active TB disease are also advised to get tested. Similarly, those who have spent time in countries with high rates of TB infection may seek testing upon their return.
Interpreting Results and Next Steps
The interpretation of a TST result focuses on measuring the diameter of the induration, which is the firm, raised, hardened area at the injection site, not surrounding redness. This measurement is taken in millimeters, and the threshold for a positive result depends on a person’s risk factors. For instance, an induration of 5 millimeters or more may be considered positive in high-risk individuals, while a larger size is necessary for lower-risk populations.
A positive result from either a TST or an IGRA test indicates the person has been infected with the TB bacteria. A positive test does not automatically mean a person has Active TB Disease, which is contagious and symptomatic. Often, it signifies Latent TB Infection (LTBI), where the bacteria are present but dormant, causing no symptoms and posing no transmission risk.
Following a positive screening result, the next step is to determine if the infection is latent or active. This almost always involves a Chest X-ray to look for physical signs of active disease in the lungs. If the chest X-ray is normal and the person has no symptoms, the diagnosis is typically LTBI. The urgent care center will then recommend a referral to a primary care physician or a specialized health department.
Further testing, such as sputum samples, is necessary if the Chest X-ray shows abnormalities or if the person is experiencing symptoms like a persistent cough, fever, or unexplained weight loss. Urgent care’s role is generally limited to screening and initial diagnosis. They will refer patients with confirmed or suspected active disease for comprehensive treatment. Treatment for LTBI usually involves a course of antibiotics to prevent the infection from progressing.