| A complete medical evaluation for | | | | results from this may take four to eight |
| tuberculosis (TB) must includes a | | | | weeks for a conclusive answer. |
| medical history, a physical examination | | | | Full blood count |
| and a chest X-ray. It may include a | | | | Although a full blood count is never |
| tuberculin skin test, other scans and | | | | diagnostic, normocytic anemia and |
| X-rays, surgical biopsy, microbiologic | | | | lymphopenia are common. Neutrophilia is |
| smears and cultures. | | | | rarely found. |
| Medical history | | | | Urea and electrolytes are usually |
| The medical history includes obtaining | | | | normal, although hypocalcemia and |
| the symptoms of pulmonary TB: | | | | hyponatremia are possible in tuberculous |
| productive, prolonged cough of three or | | | | meningoencephalitis due to SIADHS. In |
| more weeks, chest pain, and hemoptysis. | | | | advanced disease, hypoalbuminemia and |
| Systemic symptoms include fever, chills, | | | | hyperglobulinemia may be present. |
| night sweats, appetite loss, weight | | | | Erythrocyte sedimentation rate is |
| loss, and easy fatigability. Other parts | | | | usually raised. |
| of the medical history include prior TB | | | | Tuberculin skin test |
| exposure, infection or disease; past TB | | | | Two tests are available: the Mantoux and |
| treatment; demographic risk factors for | | | | Heaf tests. |
| TB; and medical conditions that increase | | | | Mantoux skin test |
| risk for TB disease such as HIV | | | | The Mantoux skin test is used in the |
| infection. | | | | United States and is endorsed by the |
| Tuberculosis should be suspected when a | | | | American Thoracic Society and Centers |
| persistent respiratory illness in an | | | | for Disease Control and Prevention |
| otherwise healthy individual does not | | | | (CDC). |
| respond to regular antibiotics. | | | | If a person has had a history of a |
| Physical examination | | | | positive tuberculin skin test, another |
| A physical examination is done to assess | | | | skin test is not needed. |
| the patient's general health and find | | | | Heaf test |
| other factors which may affect the TB | | | | The Heaf test was used in the United |
| treatment plan. It cannot be used to | | | | Kingdom until 2005, and is graded on a |
| confirm or rule out TB. | | | | four point scale. The Mantoux test is |
| Chest X-ray | | | | now used. |
| In active pulmonary TB, infiltrates or | | | | The equivalent Mantoux test positive |
| consolidations and/or cavities are often | | | | levels done with 10 TU (0.1 ml 100 TU |
| seen in the upper lungs with or without | | | | ml, 1:1000) are |
| mediastinal or hilar lymphadenopathy or | | | | 0–4 mm induration (Heaf |
| pleural effusions ( tuberculous | | | | 0 to 1) |
| pleurisy). However, lesions may appear | | | | 5–14 mm induration |
| anywhere in the lungs. In disseminated | | | | (Heaf 2) |
| TB a pattern of many tiny nodules | | | | Greater than 15 mm induration (Heaf 3 to |
| throughout the lung fields is common - | | | | 4) |
| the so called milliary TB. In HIV and | | | | CDC classification of tuberculin |
| other immunosuppressed persons, any | | | | reaction |
| abnormality may indicate TB or the chest | | | | An induration (palpable raised hardened |
| X-ray may even appear entirely normal. | | | | area of skin) of more than 5-15 mm |
| Abnormalities on chest radiographs may | | | | (depending upon the person's risk |
| be suggestive of, but are never | | | | factors) to 10 Mantoux units is |
| diagnostic of, TB. However, chest | | | | considered a positive result, indicating |
| radiographs may be used to rule out the | | | | TB infection. |
| possibility of pulmonary TB in a person | | | | 5 mm or more is positive in |
| who has a positive reaction to the | | | | HIV-positive person |
| tuberculin skin test and no symptoms of | | | | Recent contacts of TB case |
| disease. | | | | Persons with nodular or fibrotic changes |
| A variant of the chest X-Ray, | | | | on CXR consistent with old healed TB |
| abreugraphy (from the name of its | | | | Patients with organ transplants and |
| inventor, Dr. Manuel Dias de Abreu) was | | | | other immunosuppressed patients |
| a small radiographic image, also called | | | | 10 mm or more is positive in |
| miniature mass radiography (MMR) or | | | | Recent arrivals (less than 5 years) from |
| miniature chest radiograph. Though its | | | | high-prevalent countries |
| resolution is limited (it doesn't allow | | | | Injection drug users |
| the diagnosis of lung cancer, for | | | | Residents and employees of high-risk |
| example) it is sufficiently accurate for | | | | congregate settings (e.g., prisons, |
| diagnosis of tuberculosis. | | | | nursing homes, hospitals, homeless |
| Much less expensive than traditional | | | | shelters, etc.) |
| X-Ray, MMR was quickly adopted and | | | | Mycobacteriology lab personnel |
| extensively utilized in some countries, | | | | Persons with clinical conditions that |
| in the 1950s. For example, in Brazil and | | | | place them at high risk (e.g., diabetes, |
| in Japan, tuberculosis prevention laws | | | | prolonged corticosteroid therapy, |
| went into effect, obligating ca. 60% of | | | | leukemia, end-stage renal disease, |
| the population to undergo MMR screening. | | | | chronic malabsorption syndromes, low |
| The procedure went out of favor, as the | | | | body weight, etc) |
| incidence of tuberculosis dramatically | | | | Children less than 4 years of age, or |
| decreased, but is still used in certain | | | | children and adolescents exposed to |
| situations, such as the screening of | | | | adults in high-risk categories |
| prisioners and immigration applicants.. | | | | 15 mm or more is positive in |
| Laboratory | | | | Persons with no known risk factors for |
| Mycobacterium tuberculosis produces the | | | | TB |
| antigens early secretory antigen target | | | | (Note: Targeted skin testing programs |
| 6 (ESAT-6) and culture filtrate protein | | | | should only be conducted among high-risk |
| 10 (CFP-10). These antigens are not | | | | groups) |
| present in non-tuberculous mycobacteria, | | | | A tuberculin test conversion is defined |
| nor in BCG vaccine. | | | | as an increase of 10 mm or more within a |
| The blood tests QuantiFERON-TB Gold and | | | | 2-year period, regardless of age. |
| T-SPOT.TB use these antigens to detect | | | | BCG vaccine and tuberculin skin test |
| people with tuberculosis. Lymphocytes | | | | There is disagreement on the use of the |
| from the patient's blood are cultured | | | | Mantoux test on people who have been |
| with the antigens. If the patient has | | | | immunised with BCG. The US |
| been exposed to tuberculosis before, T | | | | recommendation is that in administering |
| lymphocytes produce interferon in | | | | and interpreting the Mantoux test, |
| response. The test then uses ELISA to | | | | previous BCG vaccination should be |
| detect the interferon ?. | | | | ignored; the UK recommendation is that |
| QuantiFERON-TB Gold quantifies the | | | | interferon-? tests should be used to |
| amount of interferon ? when whole blood | | | | help interpret positive tuberculin |
| is exposed to the antigens. T-SPOT.TB | | | | tests, also, the UK do not recommend |
| counts the number of activated T | | | | serial tuberculin skin testing in people |
| lymphocytes. These tests are called | | | | who have had BCG (a key part of the US |
| interferon ? tests and are not | | | | strategy). In their guidelines on the |
| equivalent. | | | | use of Quantiferon Gold the US Centers |
| Guidelines for the use of the FDA | | | | for Disease Control and Prevention state |
| approved QuantiFERON-TB Gold were | | | | that whereas Quantiferon Gold is not |
| released by the CDC in December 2005. | | | | affected by BCG innoculation tuberculin |
| The enzyme linked immunospot (ELISPOT) | | | | tests can be affected. In general the US |
| blood test is another blood test | | | | approach is likely to result in more |
| available in the UK that may replace the | | | | false positives and more unnecessary |
| skin test for diagnosis. PMID 14586040 | | | | treatment with potentially toxic drugs; |
| Microbiological studies | | | | the UK approach in in theory, as |
| Sputum smears and cultures should be | | | | sensitive and should also be more |
| done for acid-fast bacilli if the | | | | specific, because of the use of |
| patient is producing sputum. The | | | | interferon-? tests. |
| preferred method for this is | | | | Under the US recommendations, latent TB |
| fluorescence microscopy | | | | infection (LTBI) diagnosis and treatment |
| (auramine-rhodamine staining), which is | | | | for LTBI is considered for any |
| more sensitive than conventional | | | | BCG-vaccinated person whose skin test is |
| Ziehl-Neelsen staining. | | | | 10 mm or greater, if any of these |
| If no sputum is being | | | | circumstances are present: |
| produced,examination of gastric juice, a | | | | Was contact of another person with |
| laryngeal swab, bronchoscopy or fine | | | | infectious TB |
| needle aspiration should be considered. | | | | Was born or has resided in a high TB |
| Other mycobacteria are also acid-fast. | | | | prevalence country |
| Even if sputum smear is negative, | | | | Is continually exposed to populations |
| tuberculosis must be considered and is | | | | where TB prevalence is high. |
| only excluded after negative cultures. | | | | Contact screening |
| Further PCR or gene probe tests can | | | | When someone is diagnosed with |
| distinguish M. tuberculosis from other | | | | tuberculosis, all their close contacts |
| mycobacteria. If this is not available, | | | | should be screened for TB with a |
| a culture of the AFB can distinguish the | | | | tuberculin skin test or a chest x-ray or |
| various forms of mycobacteria, although | | | | both. |