diagnosis for tuberculosis

DIAGNOSIS
SIGNS AND SYMPTOMS
• Cough
• Hemoptysis
• Fever and night sweats
• Weight loss
• Malaise
• Painless adenopathy
• Pleuritic chest pain
• Hepatosplenomegaly
• Late findings: Renal, bone, or CNS disease
History
• Recent travel to or immigration from high-prevalence country
• Exposure to high-risk populations (see "Risk Factors"), or to known infected person
• HIV status/risk factors
Physical Exam
• Often normal
• May note rales on lung exam.
• Specific findings vary based on organ involvement.
TESTS
Lab
• Persons with TB should be tested for HIV; if positive, get CD4 count.
• Baseline liver enzymes, bilirubin, creatinine, CBC with platelet count
• If using ethambutol: Baseline visual acuity and color discrimination
• If high risk: Test for hepatitis B and C
• If extrapulmonary suspected: Urine, CSF, bone marrow, and liver biopsy for culture
• Nonspecific laboratory findings include
- Anemia
- Monocytosis
- Thrombocytosis
- Hypergammaglobulinemia
- SIADH
- Sterile pyuria
- Steroids: False-negative skin test
• Factors that may yield false-negative skin test
- Recent viral infections
- New (10 weeks) infection
- Severe malnutrition
- HIV
- Anergy
- Age 6 months
- Overwhelming TB
Imaging
• Chest radiograph
- With primary TB: May show infiltrate with or without effusion, atelectasis, or adenopathy
- With recrudescent TB: Cavitary lesions and upper-lobe disease with hilar adenopathy common
- HIV: Atypical findings with primary infection, right upper-lobe atelectasis
• CT chest: Good sensitivity
Diagnostic Procedures/Surgery
• PPD: 5 units (0.1 cc) intermediate-strength intradermal injection into volar forearm. Measure induration at 48-72 h
• PPD positive if induration
- >5 mm and HIV infection (or suspected), immunosuppressed, recent TB contact, clinical evidence of disease on chest film
- >10 mm and age 4 years or other risk factors
- >15 mm and age >4 years and no risk factors
- 2-step test if patient has no recent PPD, age >55, nursing home resident, prison inmate, or health care worker. Administer second test 1-3 weeks after initial one; interpret as usual.
• Drugs that may alter PPD results
- BCG: False-positive skin test, but unreliable and should not influence decision to treat latent tuberculosis infection
 QuantiFERON whole blood assay not affected by BCG vaccine (2)[A]
• 3 different morning sputum samples for acid-fast bacilli (AFB) stain and culture; use aerosol induction, gastric aspirate (children), or bronchoalveolar lavage if needed
• If positive AFB, begin treatment immediately
• Culture and sensitivity guide treatment
Pathological Findings
• AFB stains positive
• Biopsy may show granulomas with central caseating necrosis.