What is the minimum level of hemoglobin required for survival?

Hemoglobin is a protein found in red blood cells which helps to transport oxygen throughout the body. There is a normal, healthy range for hemoglobin levels, and most healthy people fall within this range when they have a blood test. The healthy range of hemoglobin may vary depending on factors such as age and biological sex.

The normal ranges for children are 14-24 g/dL for newborn babies and 9.5-13 g/dL for infants. The normal ranges for adult males is 13.8-17.2 g/dL, and for adult females, 12.1-15.1 g/dL. Children who have grown out of infancy but have  not quite finished puberty are expected to fall somewhere between the infant and adult ranges, typically around 13 or 14 g/dL depending on age and biological sex.

Someone who has levels of hemoglobin which are clinically low or low but within normal range may experience fatigue, weight loss, shortness of breath, and skin which is paler than normal. Some conditions cause a chronically low level of hemoglobin, like hypothyroidism, cancer, and chronic anemia. In such cases, low hemoglobin and its cause should be closely followed by a physician.

There is no one, standard minimum level of hemoglobin agreed upon in the medical community. Hemoglobin levels are highly variable from person to person and may even shift within one person over the course of several days. In the past, it was generally agreed upon by hematologists and those concerned with blood transfusion that 10g/dL of hemoglobin was the absolute minimum acceptable amount. More recently, this value has been questioned, as hemoglobin levels are only one facet of respiration and hemostasis. While low hemoglobin increases risk of death, it is the stress placed on the heart and poor oxygenation to the brain and other tissues which would be the actual cause of death. 

If you or someone you know has low hemoglobin levels, please see a physician to discuss how you can manage this condition. Having adequate protein intake and getting exercise are good ways to ensure the health of your red blood cells.