The clinical manifestations vary with the age, degree and rapidity of onset, presence of subjacent illness and other factors. Mild anemia are often assymptomatic. Dizziness, headache, syncope, tinnitus or vertigo, irritability, difficulty sleeping or concentrating are more frequent in severe chronic anemia. In old people, angina pectoris can be an important clinical manifestation. Females commonly develop abnormal menstruation, both amenorrhea and increased bleeding.
Males can develop decrease in libido and impotence.
The main consequence of anemia is tissue hypoxia. If anemia has developed rapidly, there may not be adequate time for compensatory adjustments to take place, so there is a sudden marked contraction of intravascular volume, resulting in postural hypotension, fall in cardiac output, shunting of blood from skin to central organs, sweating, restlessness, thirst and air hunger. If anemia has slowly instalation, many adaptations occur for the oxygen mantainance, such as increasing of plasmatic volume and right shift of the oxygen-hemoglobin dissociation curve. In the hystory is important to ask about duration and time of onset, other subjacent illness, associated symptoms related with one specific etiology, family history, hemotransfusion, blood loss and drug exposure. Bone marrow aspiration is useful and critical in the workup of any unexplained anemia, specially in underproductions anemia.