Aim: Familial Mediterranean fever (FMF) is the most frequent periodic syndrome characterised by recurrent attacks of polyserositis. However, recent studies revealed that there might be an ongoing subclinical inflammation between the attacks. As nitric oxide (NO) and adrenomedullin (AM) are both synthesised in the endothelium, and mediates many functions within immune system, we considered them to be an interesting target of investigation in FMF.
Methods: Fifteen children with FMF receiving regular colchicine, ranging in age from 3 to 16 years, were investigated in comparison with 15 healthy age- and sex-matched controls. The mean age of the patients was 9.7 +/- 3.9 years. Total nitrite, a stable product of NO, was quantitated by means of the Griess reaction, while AM was measured by HPLC.
Results: Plasma-urinary AM and total nitrite levels were significantly higher in children with FMF. Plasma AM levels (pmol/mL) in patients and controls were 40.95 +/- 5.99 vs. 34.86 +/- 5.24, P < 0.05, and urinary AM excretion (pmol/mg creatinine) was 51.16 +/- 28.15 vs. 37.5 +/- 24.26, P < 0.05 respectively. Plasma total nitrite levels (micromol/L) in patients and controls were 44.80 +/- 10.36 vs. 32.13 +/- 9.28, P < 0.05, and urinary nitrite excretion (micromol/mg creatinine) was 2.24 +/- 1.71 vs. 1.09 +/- 0.96, P < 0.05 respectively.
Conclusion: This study considered that AM and NO may have a role in the immuno-inflammatory process of FMF, although, whether these act to preserve, or protect against, further inflammatory injury is not clear. Our results further supports the hypothesis that these patients have subclinical inflammation between attacks.