Investigations

Recommended initial evaluation of sarcoidosis includes:

• a detailed history from the patient - inquire about
  • any extrapulmonary symptoms which may relate to skin, eyes, and joints involvement
  • occupational and environmental dust exposure - may indicate hypersensitive pneumonitis
  • family history of sarcoidosis (1)
• physical examination
  • should be carried out according to the symptoms
  • identify any possible biopsy sites e.g. - lymphadenopathy, skin lesions, old scars, and tattoos (1)
• chest radiology
  • used for staging which is of prognostic value (1)
  • bilateral hilar lymphadenopathy (BHL) is seen in close to three quarters of patients (2)
• lung function tests - may show reduced transfer factor and a restrictive ventilatory defect
• blood tests
  • full blood count
  • liver function test
  • serum (and urinary) electrolytes and calcium - hypercalcaemia and hypercalciuria are common
  • serum angiotensin converting enzyme (ACE) - may be raised in acute sarcoidosis, however, the low specificity of the test renders it useful only for monitoring the severity of disease (1)
• ECG - findings suggestive of latent cardiac sarcoidosis are arrhythmias and conduction delay (3)
  • sarcoidosis and the ECG - click here for example ECGs and further explanation
    
    
• tuberculin tests up to 1 in 100 are negative in 75% of patients
• ophthalmology review - slit lamp examination to recognize symptomatic and potentially sight threatening uveitis (1)
• high resolution CT
  • is a standard investigation in hospital setting and can be used to assess the involvement and to identify abnormal nodes for biopsy (1).
  • may reveal the presence of parenchymal disease, not revealed by a chest radiograph
• tissue biopsy:
  • samples: lymph nodes, bronchial, transbronchial, liver, skin, eyelids and muscle
  • transbronchial samples are histologically positive in 90% of patients with pulmonary sarcoidosis
• Kviem test:
  • positive in 80% of cases of acute sarcoidosis
  • not used now because of risk of infection
• sputum should be examined microscopically and cultured to exclude the presence of Mycobacterium tuberculosis.

Reference:

• (1) Dempsey OJ et al. Sarcoidosis. BMJ. 2009 Aug 28;339:b3206
• (2) Lynch JP 3rd et al. Pulmonary sarcoidosis. Semin Respir Crit Care Med. 2007;28(1):53-74.
• (3) Bradley B et al.Interstitial lung disease guideline: the British Thoracic Society in collaboration with the Thoracic Society of Australia and New Zealand and the Irish Thoracic Society. Thorax. 2008;63 Suppl 5:v1-58.