Basic Initial Tests for Diagnosing Familial Mediterranean Fever (FMF)
The basic initial tests for diagnosing Familial Mediterranean Fever (FMF) should include C-reactive protein (CRP) and serum amyloid A (SAA) protein measurements, complete blood count, genetic testing for MEFV mutations, and monitoring of liver enzymes, kidney function, and proteinuria. 1
Laboratory Tests for Initial Diagnosis
- CRP and SAA are essential inflammatory markers that should be measured during and between attacks to assess disease activity and subclinical inflammation 1
- Complete blood count typically shows elevated white blood cell count and high sedimentation rate during attacks 2
- Liver enzyme tests should be performed as baseline measurements before starting treatment 1
- Kidney function tests and urinalysis for proteinuria are crucial to detect early signs of amyloidosis, the most severe complication of FMF 1
- Creatinine phosphokinase (CPK) should be measured as a baseline before treatment initiation 1
Genetic Testing
- Genetic testing for MEFV mutations should be performed in all suspected FMF cases, particularly focusing on exon 10 mutations 1, 3
- The most common pathogenic mutations to test for include M694V, M694I, M680I, V726A, and E148Q 2, 4
- The M694V mutation is particularly important to identify as it is associated with more severe disease and higher risk of amyloidosis 2, 4
Clinical Assessment Tools
- Documentation of attack frequency, duration, and characteristics (fever, peritonitis, pleuritis, arthritis) is essential 1, 5
- Autoinflammatory diseases activity index (AIDAI) can be used to assess disease activity, though it has limitations 1, 5
- Patient diaries documenting attacks should be maintained to establish patterns 1
Functional Testing
- An ex vivo colchicine assay may be helpful in cases where genetic testing is inconclusive, as it can distinguish between patients with classical FMF mutations and those with variants of uncertain significance 3
Important Considerations
- Standard laboratory tests may be normal between attacks, so timing of testing is crucial 2
- During attacks, expect to see elevated acute phase reactants, including fibrinogen, C-reactive protein, and various globulins 2
- No single test is diagnostic for FMF; diagnosis relies on a combination of clinical presentation, laboratory findings, response to colchicine, and genetic testing 1, 6
- Testing should be interpreted by a physician with experience in FMF, as recommended by EULAR guidelines 1