HIF1A and transient ischemic attack: Hypoxia inducible factor 1alpha (HIF-1α) serum level was significantly increased at T0, in both AIS and TIA patients, in comparison to C (both p < 0.01 vs. C) and it decreased in both AIS and TIA patients at 24 h and at 48 h, in comparison to T0 (both p < 0.01 vs. T0).