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## Definition of Anemia Anemia is a reduction in hemoglobin (Hb) concentration below reference values for age and sex. The reference values also vary with race, altitude. * WHO defines anemia as Hb level below 12 g/dL in women and 13 g/dL in men. * Reduction of Hb is usually accompanied by a fall...

## Definition of Anemia Anemia is a reduction in hemoglobin (Hb) concentration below reference values for age and sex. The reference values also vary with race, altitude. * WHO defines anemia as Hb level below 12 g/dL in women and 13 g/dL in men. * Reduction of Hb is usually accompanied by a fall in red cell count and hematocrit (Hct) but these may be normal in some patients with anemia. ### Anemia * Normal amount of red blood cells * Normal amount of white blood cells * Anemia * Low red blood cells * Poor oxygenation of tissues ### Changes in plasma volume affect Hb concentration and can affect the diagnosis of anemia * Reduction in plasma volume (e.g., in dehydration) may: * lead to hemoconcentration with apparent increase in Hb level. * underestimate or even mask anemia * Increase in plasma volume (e.g., in pregnancy) may: * lead to hemodilution with apparent decrease in Hb level. * cause wrong diagnosis of anemia. Anemia is rarely a disease by itself. It is mostly a manifestation or consequence of an underlying (genetic or acquired) disease. ## Clinical Features of Anemia Symptoms and signs of anemia are mainly due to: * Tissue hypoxia: * Fatigue, dyspnea on exertion etc * Compensatory attempts: Tachycardia, hyperventilation etc These include: * Fatigue, weakness * Tiredness, lassitude, reduced exercise tolerance * Generalized muscular weakness * Palpitation and dyspnea (during activity) * Pallor of mucous membranes (color of skin is not a reliable sign) * Headache * Faintness * Giddiness * Tinnitus * Decreased concentration ability * Menstrual changes (in females)