Some changes associated with hydroxyurea treatment (increased nitric oxide and HbF) would be expected to protect against malaria, but the data on hydroxyurea-related endothelial changes thought to be important in malaria pathogenesis (e.g. intracellular adhesion molecule (ICAM)-1, von Willebrand factor (VWF), tumor necrosis factor (TNF)-α) is unclear, with some studies suggesting that these factors might be increased with hydroxyurea and others suggesting no difference or a decrease.