Hemoglobin (Hb)

Hemoglobin is a tetrameric metalloprotein found within erythrocytes (red blood cells), comprising two alpha and two beta subunits in adults (HbA); each subunit contains an iron-bound heme group capable of reversibly binding an oxygen molecule, enabling the transport of up to four oxygen molecules per hemoglobin molecule[2][3][6]. The process is highly regulated and demonstrates cooperative and allosteric properties, with hemoglobin’s affinity for oxygen modulated by factors such as pH, carbon dioxide, temperature, and 2,3-bisphosphoglycerate[2][3][6][7]; this ensures efficient uptake in the lungs and release in metabolically active tissues. Besides oxygen transport, hemoglobin assists in the transport of carbon dioxide and buffers blood pH. Red cell lysis or abnormal hemoglobin structure can impair function and result in disease, while targeted drugs and interventions (including erythropoiesis stimulators and hemoglobin modifiers) can enhance oxygen delivery or ameliorate disease symptoms[6]. Safety concerns include anemia, dysfunctional hemoglobin variants, and complications during therapies that alter hemoglobin levels or properties[1][2][3][6][7].

Other names

HemoglobinHaemoglobinAdult hemoglobin (HbA)Fetal hemoglobin (HbF)OxyhemoglobinDeoxyhemoglobin

Increasing hemoglobin levels (e.g., erythropoiesis stimulation) improves oxygen-carrying capacity - Inducing fetal hemoglobin (hydroxyurea) ameliorates sickle cell disease - Iron supplementation treats iron-deficiency anemia by supporting hemoglobin synthesis - Blood substitutes temporarily replace or supplement oxygen transport - Antidotes (e.g., high-flow O₂ or methylene blue) treat hemoglobin dysfunction (CO poisoning, methemoglobinemia)