RBP4 and triple-A syndrome: Intriguingly, five negative acute-phase proteins (retinol-binding protein 4 [17], fibronectin [18], serotransferrin [19], histidine-rich glycoprotein [20] and inter-α-trypsin inhibitor heavy chain H2 [21]) were decreased in postsurgical sera compared with those in presurgical sera of both AAA and TAA patients.