The hemoglobin in the red cells carries oxygen needed for good health and life. So if a person has lost a lot of blood, it might seem logical just to replace it. Normally you have about 14 or 15 grams of hemoglobin in every 100 cubic centimeters of blood. (Another measure of the concentration is hematocrit, which is commonly about 45 percent.) The accepted “rule” was to transfuse a patient before surgery if his hemoglobin was below 10 (or 30 percent hematocrit). The Swiss journal Vox Sanguinis (March 1987) reported that “65% of [anesthesiologists] required patients to have a preoperative hemoglobin of 10 gm/dl for elective surgery.”

But at a 1988 conference on blood transfusion, Professor Howard L. Zauder asked, “How Did We Get a ‘Magic Number’?” He stated clearly: “The etiology of the requirement that a patient have 10 grams of hemoglobin (Hgb) prior to receiving an anesthetic is cloaked in tradition, shrouded in obscurity, and unsubstantiated by clinical or experimental evidence.” Imagine the many thousands of patients whose transfusions were triggered by an ‘obscure, unsubstantiated’ requirement!

Some might wonder, ‘Why is a hemoglobin level of 14 normal if you can get by on much less?’ Well, you thus have considerable reserve oxygen-carrying capacity so that you are ready for exercise or heavy work. Studies of anemic patients even reveal that “it is difficult to detect a deficit in work capacity with hemoglobin concentrations as low as 7 g/dl. Others have found evidence of only moderately impaired function.”—Contemporary Transfusion Practice, 1987.

While adults accommodate a low hemoglobin level, what of children? Dr. James A. Stockman III says: “With few exceptions, infants born prematurely will experience a decline in hemoglobin in the first one to three months . . . The indications for transfusion in the nursery setting are not well defined. Indeed, many infants seem to tolerate remarkably low levels of hemoglobin concentration with no apparent clinical difficulties.”—Pediatric Clinics of North America, February 1986.

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“Some authors have stated that hemoglobin values as low as 2 to 2.5 gm./100ml. may be acceptable. . . . A healthy person may tolerate a 50 percent loss of red blood cell mass and be almost entirely asymptomatic if blood loss occurs over a period of time.”—“Techniques of Blood Transfusion,” 1982.