Can a small amount of haemoglobin kill you? An observational study of 2059 patients who have undergone coronary bypass surgery certainly indicates it might.
Patients with haemoglobin levels less than 100 g/L are usually given a preop transfusion to compensate for blood loss during surgery.
Now, the results of the study, carried out by researchers at Imperial College and Hammersmith Hospital in London, suggest that, though patients with low haemoglobin levels can cope well with a variety of surgical operations, coronary artery bypass grafting (CABG) is not one of them.
Indeed, with CABG, mortality rates were five times higher in such patients - mostly men. Female patients, who normally have lower haemoglobin levels than men, showed no such difference, possibly because they are better able to tolerate a lower level of haemoglobin (Lancet, 2002; 359: 1747-8).