In a significant proportion of patients with familial Mediterranean fever (FMF), serum amyloid A (SAA) remains elevated during attack-free periods, thereby increasing the risk of developing amyloidosis. The aim of the study was to determine various correlates of elevated SAA and evaluate the role of SAA measurement in the diagnosis and management of FMF.
We reviewed the medical files of all 204 patients from our FMF center in whom SAA measurements were performed. SAA levels and the resulting diagnostic and therapeutic decisions were analyzed in relation to the reasons of SAA testing and to several clinical and genetic parameters.
SAA measurements were made for diagnostic purposes in 29% of the patients. In the remainder, SAA measurements were used for adjustment of colchicine dose. Elevated SAA levels are found in a third of FMF patients during an attack-free period. The highest rate of elevated SAA levels was found in patients with proteinuria (60% of this patient group), followed by noncompliant (40%) and genetically positive asymptomatic patients (38%). Elevated SAA levels during remission were associated with family history of FMF, M694V homozygosity, and elevated C-reactive protein (CRP) (P<0.05 for each). Patients homozygous for the M694V mutation had the highest level of SAA. SAA measurement led to a change in colchicine dose in 30% of the patients, predominantly in noncompliant patients and patients with proteinuria or with atypical manifestations.
Measurement of SAA level may help in the diagnosis of FMF and in adjustment of the colchicine dose.