GSTM1 and ischemic stroke: Elevated hemoglobin (Hb) concentration has been shown, in a large cohort of Scandinavian blood donors, to be associated with an increased risk of vascular events—e.g., for men, the levels of Hb 16.0–17.4 g/dL carried a risk of ischemic stroke with an HR of 1.55 (1.38–1.75) [26].