GSTM1 and Recurrent upper respiratory tract infections: Among the temporary deferral causes, the most common reason for overall deferral among blood donors was low hemoglobin (Hb) level (38.3%), followed by upper respiratory tract infections (URTIs, 8.4%), high blood pressure (7.0%), low blood pressure (5.6%), being on medication (5.5%), inadequate sleep (4.7%), and low body weight (4.6%).