With respect to blood chemistry, the usual findings of thrombocytopenia, leukocytosis and mildly elevated creatine-kinase blood levels were present [21, 42] . Regrettably, the lymphocyte count was not recorded. In viral infections, thrombocytopenia occurred frequently. Although the mechanisms by which the 2009 influenza A (H1N1) virus causes thrombocytopenia are unknown, its lack of resolution is a marker of poor prognosis. Both leukocytosis and leucopenia have been found in hospitalized patients with 2009 influenza A (H1N1) [2, 43] ; in our study, persistent leukocytosis was associated with increased mortality. LDH elevations have been previously described in fatal cases [2] , which corresponded to our finding of higher LDH levels in non-survivors at all time points. Such elevations have also been reported in seasonal influenza [44] . In experimental studies, increased LDH is a marker of human fetal membrane cell apoptosis induced by influenza virus [45] . Finally, multiorgan failure was frequent, and predictably more severe in non-survivors.