Anemia: Body Adaptation and Symptoms

Anemia or decreased concentration of hemoglobin in the blood - may be due to various causes, and the most common is the lack of iron, but it can also be a symptom of an underlying disorder.

Anemia is considered when the concentration of hemoglobin in the blood decreases, although the red blood cells are normal or even high. The reference that restricting the concentration of hemoglobin in the blood can vary depending on the population analyzed, since it depends on various factors such as age, sex, environmental conditions and dietary habits. Anemia is one of the most frequent causes of consultation for three main reasons:

• High incidence in children, women, youth or adult subjects with deficiencies in their diet (lack of iron and folic acid, especially).
• It tends to be associated with many other diseases, which is a symptom of the underlying disorder.
• High frequency in certain ethnic groups (associated with malnutrition and is widespread, especially in developing countries where people do not have the resources to maintain adequate food).

In many countries, the most common cause is lack of iron (iron deficiency anemia), whose incidence is particularly high in young women and growing children. Clinical manifestations of anemia (anemia syndrome) is generated from the operation of the various mechanisms of adaptation to deal with a decrease in tissue oxygenation (hypoxia) and mainly depends on the patient's age, how fast the establishment and the state of the cardiovascular system.

Body Adaptation to Anemia

The decline in blood hemoglobin levels are always responded by the body with increased synthesis of erythropoietin. The mechanism that involved in this process is directly related to hypoxia (lack of oxygen in tissues) - the main mechanism of adaptation to the anemia. Along with this, they implement another coping mechanism that occurs in the hematopoietic system and cardiovascular system.

Hematopoietic system produces a stimulation of erythropoiesis (red blood cell synthesis). The cardiovascular system responds, first through vasoconstriction widespread (preferably on skin, kidney, and spleen area) and subsequently, with the redistribution of blood volume and the increase in plasma volume.

Erythropoietin stimulation
It is a direct consequence of the increase in the concentration of erythropoietin synthesis, and it aims to increase the number of erythrocytes (red blood cells in blood) circulation.

Better use of available hemoglobin
Is achieved by increasing the intraeritrocitaria concentration (within erythrocytes) of 2,3 diphosphoglycerate (DPG), as this compound decreases the affinity of hemoglobin for oxygen. This effect facilitates the release of oxygen to tissues.

Adaptation of the cardiovascular system
Faced with anemia, the body responds immediately with a redistribution of blood, which aims to ensure oxygenation of vital organs. Two simultaneous phenomena occur in this process:

Redistribution of blood flow
On the phenomenon of redistribution, a vasoconstriction from less deprived areas occurs, for example, the skin (pallor) and kidney, to derive blood to the most critical regions, for example, the brain. That is, the blood vessels on less important organs are closed, and blood that cannot pass through them is diverted to impersonate other major organs.

Increasing cardiac output
The largest debit or cardiac output is a response to tissue hypoxia; i.e., it increases the amount of blood pumped by the heart. This phenomenon is not developed until the concentration of hemoglobin in blood drops below 70 g / l. Clinically; increased cardiac output is manifested by tachycardia and functional appearance of systolic murmurs (produced by the blood out of the heart without having any pathology in the cardiac structures). If anemia is very intense and happens suddenly (acute anemia), a decrease in venous pressure can facilitate the development of hypovolemic shock. On the other hand, when the formation is slow (chronic anemia), then the volume of plasma characteristics progressively increased to maintain blood volume and prevent shock.

Signs and Symptoms of Anemia

The anemic syndrome is formed by a set of signs and symptoms that show the decrease in hemoglobin and development of compensatory mechanism. The main symptoms of anemia are:

• Pallor: it is one of the most characteristic signs of anemia and a direct consequence of the widespread vasoconstriction (closing of the blood vessels) and the decrease in the concentration of hemoglobin in blood.
• Asthenia: is a general symptom closely linked to anemia (the anemic individual feels "tired").
• Dyspnea: subjective sensation of breathlessness.
• Muscle fatigue: even with small efforts.
• Cardiovascular manifestations: tachycardia and palpitations which are constant in moderate or severe anemia cases, especially when it founds abruptly. In a slow onset chronic anemia, the only noticeable sign of anemia is a functional systolic murmur (noise which makes the blood out of the heart). If anemia is very intense, it will add tachypnea (rapid breathing) or loss of consciousness.
• Neurological disorders: changes in vision. Cephalalgia (headache). When hemoglobin drops below 30 g/l (severe anemia), signs of cerebral hypoxia, headache, vertigo and even coma may occur.
• Neuromuscular manifestations: consists mainly of changing behavior, headaches, dizziness, visual disorders, insomnia, inability to concentrate and occasionally disorientation
• Changes in menstrual period: the existence of heavy periods (hipermenorrea) is the most common cause of anemia in young women, although it is usually a moderate anemia (Hb: 90-110 g/l). However, when anemia is more intense, it is usually show a reduction of menstrual rhythm, with a tendency to amenorrhea. What happens is that, against the decrease of hemoglobin, the body reacts to decrease, or even annulling, hematic loss.
• Renal disorders: there is a water retention which can lead to the appearance of edema or swelling in the legs.
• Digestive disorders: consist of anorexia, nausea and occasional constipation.