Background: A transfusion threshold of 7 g per dL (70 g/L) of hemoglobin has been proposed for patients, although scant human data are available to support this recommendation.
Study design and methods: The medical community's experience with Jehovah's Witnesses was examined, in order to assess the lowest tolerable hemoglobin concentration and the lower transfusion threshold of 7 g per dL (70 g/L) of hemoglobin. A MEDLINE search was conducted to capture medical and surgical reports involving Jehovah's Witnesses from 1970 through early 1993.
Results: Sixty-one reports of untransfused Jehovah's Witnesses with hemoglobin concentrations < or = 8 g per dL (80 g/L) or hematocrits < or = 24 percent (0.24) were identified. Of 50 reported deaths, 23, as stated in the original reports, were primarily due to anemia. Except for three patients who died after cardiac surgery, all patients whose deaths were attributed to anemia died with hemoglobin concentrations < or = 5 g per dL (50 g/L). Twenty-five survivors were reported with hemoglobin < or = 5 g per dL (50 g/L).
Conclusion: These data have significant limitations but suggest that survival, without transfusion, is possible at low hemoglobin concentrations, while mortality with an unknown incidence is encountered at hemoglobin concentrations below 5 g per dL (50 g/L).