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Education Materials > Publications > Self-Study Modules on TB > Module 3 > Diagnosis of TB > The Medical History

Self-Study Modules on Tuberculosis

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Module 3: Diagnosis of Tuberculosis Infection and Disease

The Medical History

  1. Exposure to TB. One important part of the medical history is asking the patient about his or her exposure to TB. Patients should be asked whether they have spent time with someone who has infectious TB. Some people may have been exposed to TB in the distant past, when they were children. Others may have been exposed more recently.

    Anyone who has been exposed to TB may have TB infection. Some people become infected with M. tuberculosis without knowing that they were exposed to it. The risk of being exposed to TB is higher for some occupations (for example, some health care workers) and in some residential facilities (for example, nursing homes or correctional facilities).

  2. Symptoms of TB disease. Another important part of the medical history is checking for symptoms of TB disease. People with TB disease may or may not have symptoms. However, most patients with TB disease have one or more symptoms that led them to seek medical care. Occasionally, TB is discovered during a medical examination for an unrelated condition (for example, when a patient is given a chest x-ray before undergoing surgery). Usually, when patients do have symptoms, the symptoms have developed gradually, and they have been present for weeks or even months.

    Pulmonary TB disease usually causes one or more of the following symptoms:

    • Coughing
    • Pain in the chest when breathing or coughing
    • Coughing up sputum (phlegm from deep in the lungs) or blood

    The general symptoms of TB disease (pulmonary or extrapulmonary) include

    • Weight loss
    • Fatigue
    • Malaise
    • Fever
    • Night sweats

    The symptoms of extrapulmonary TB disease depend on the part of the body that is affected by the disease. For example, TB of the spine may cause pain in the back; TB of the kidney may cause blood in the urine.

    All of these symptoms may be caused by other diseases, but they should prompt the clinician to suspect TB disease.

  3. Previous TB infection or TB disease. During the medical history, the clinician should ask the patient whether he or she has ever been diagnosed with or treated for TB infection or disease.
    • Patients known to have a positive skin test reaction probably have TB infection. If they were infected within the past 2 years, they are at high risk for TB disease.
    • Patients who have had TB disease before should be asked when they had the disease and how the disease was treated. If the regimen prescribed was inadequate or if the patient did not follow the recommended treatment, TB may recur, and it may be resistant to one or more of the drugs used.

  4. Risk factors for developing TB disease. A fourth part of the medical history is checking for risk factors for developing TB disease. The following conditions appear to increase the risk that TB infection will progress to disease:
    • Infection with HIV, the virus that causes AIDS
    • Alcohol abuse and drug injection
    • Recent TB infection (within the past 2 years)
    • Chest x-ray findings suggestive of previous TB
    • Diabetes mellitus
    • Silicosis
    • Prolonged therapy with corticosteroids
    • Immunosuppressive therapy
    • Certain types of cancer (e.g., leukemia, Hodgkin's disease, or cancer of the head and neck)
    • Severe kidney disease
    • Certain intestinal conditions
    • Low body weight (10% or more below ideal)

    Clinicians should determine whether patients have any of these conditions. In particular, HIV infection greatly increases the risk that TB infection will progress to TB disease.

    A physical examination is an essential part of the evaluation of any patient. It cannot confirm or rule out TB disease, but it can provide valuable information about the patient's overall condition and other factors that may affect how TB disease is treated if it is diagnosed.


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Division of Tuberculosis Elimination -

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