Relationship between serum cystatin C level and M694V homozygosity in patients with familial Mediterranean fever

Aim: In this study we aimed to evaluate the relation of cystatin C with proteinuria, estimated glomerular filtration rate (eGFR), and disease activity in patients with familial Mediterranean fever (FMF). Material and Methods: One hundred twenty four patients with FMF and 66 healthy controls were included in the study. Complete blood count (CBC), acute phase reactants (erythrocyte sedimentation rate, c-reactive protein), routine biochemical tests, thyroid function tests (TFT), FMF gene analysis, 24-hour urine analysis and serum cystatin C levels were evaluated. Results: Patients and controls had similar cystatin C levels. A significant negative relationship between creatinine clearance and cystatin C, and a significant positive relationship between microalbuminuria and cystatin C were detected (p=0.008 and p=0.005, respectively) in FMF patients. Cystatin C levels were significantly higher in M694V homozygotes than in M694V mutation-negative patients (p=0.016). Cystatin C levels were higher in men than in women in FMF and control groups (p=0.008, and p=0.003, respectively). Discussion: In accordance with the literature, creatinine clearance and microalbuminuria were found to be related to serum cystatin C levels. Therefore, cystatin C or cystatin C-based eGFR measurement is important for early detection of nephropathy and early treatment of the disease.