20th February 2025

Diagnosis of sarcoidosis

Investigation findings include:

• Urine: hypercalciuria
• Bloods: possible abnormalities include abnormal FBC (may show anaemia, lymphopenia, eosinophilia or raised white cell count), raised ESR, raised calcium, raised phosphate, raised ALP, deranged U&E (although renal impairment is rare), deranged LFTs, elevated serum ACE (in around 60% of patients with acute disease)
• CXR aids with staging:
  • Stage 0 – Normal CXR
  • Stage 1 – Bilateral hilar lymphadenopathy
  • Stage 2 – Bilateral hilar lymphadenopathy and interstitial infiltrates
  • Stage 3 – Diffuse interstitial infiltrates
  • Stage 4 – Diffuse fibrosis
• HRCT: may show lymph node enlargement or calcification, fibrosis or nodules. A minority of patients have a UIP pattern on CT and this carries a worse prognosis
• Lung function tests: typically a restrictive defect with decreased TLCO and VC
• FDG-PET: used to assess inflammatory activity and aids prognostication
• Bronchoscopy: bronchoalveolar lavage may show increased lymphocytes (raised CD4:CD8 ratio)
• Biopsy: endobronchial ultrasound-guided or transbronchial biopsy of suspicious lesions shows non-caseating granulomas. Other lesions (such as skin or lymph nodes) may be biopsied to aid diagnosis