Chapter 8. Anemia

Formulating a diagnosis

Components of the diagnosis: pathogenetic variant; severity; complications

Anemia is defined for patient care as a reduction in one or more of the major red blood cell (RBC) measurements obtained as a part of the complete blood count (CBC): hemoglobin concentration, hematocrit, or RBC count. A low hemoglobin concentration and/or low hematocrit are the parameters most widely used to diagnose anemia.

More than one-quarter of the world’s population is anemic, with approximately one-half of the burden from iron deficiency.

In many cases, it is mild and asymptomatic and requires no mana­gement. The prevalence increases with age and is more common in women of reproductive age, pregnant women, and the elderly.

Anemia, like a fever, is a sign that requires investigation to determine the underlying etiology.

The pathophysiology of anemia varies greatly depending on the pri­mary cause.

Anemia can be a primary (idiopathic) disease or occur due to a chronic disease leading to malabsorption, metabolic disorders, or loss of elements ne­ces­sary for normal blood formation. The most common causes of secondary anemia are diseases of the gastrointestinal tract, liver, kidneys and female genital organs.

Quick tips

Anemic syndrome is a complex of clinical and laboratory symptoms characterized by decreased Hb levels and associated clinical manifestations.

The diagnosis of anemia is made when the detected levels of Hb in the clinical analysis of blood are below normal values, which depend on gender and are less than 120 g/L in women, and less than 130 g/L in men.

If anemia is detected in a patient, it is necessary to answer the following questions.

• What is the cause of anemia?
• What is the diagnostic minimum to determine the cause of anemia?
• What is the management of anemia?

Pathogenetic variant

• Acute posthemorrhagic anemia.
• Anemias associated with impaired erythropoiesis:
  • impaired erythrocyte maturation as a result of iron deficiency or impairment of its utilization;
  • impaired differentiation — congenital and acquired aplastic anemias;
  • hypo-proliferative anemias — B₁₂ and folate deficiency anemia (FDA).
• Hemolytic anemias.
• Anemia of chronic disease (ACD).

The classification of anemias into three groups depending on the hemoglobin content in the erythrocyte — hypochromic, normochromic, and hyperchromic — is convenient for practical work.

This classification is of practical importance in the work of an outpatient doctor since it allows suspecting one or another type of anemia based on a routine clinical blood panel and to prescribe a targeted examination. On the other hand, this classification does not affect pathogenesis and cannot be considered a reference.

The etiology of anemia depends on whether the anemia is hyporegenerative (i.e., corrected reticulocyte count <2%) or hyperegenerative (i.e., corrected reticulocyte count >2%) (table 8.1).

Table 8.1. Classification by the regeneration status

Hypoproliferative anemias are further divided by the mean corpuscular volume into microcytic anemia (MCV <80 fl), normocytic anemia (MCV 80–100 fl), and macrocytic anemia (MCV >100 fl).

Quick tips

Microcytosis is a descriptive term for RBC size smaller than the normal range. The causes are numerous, and the evaluation depends on a synthesis of clinical and laboratory information.

Anemia associated with impaired iron metabolism

Iron-deficiency anemia

The most common cause of decreased hemoglobin levels in outpatient practice is iron deficiency anemia (IDA).

Iron deficiency anemia develops when body stores of iron drop too low to support normal red blood cell production. Inadequate dietary iron, impaired iron absorption, bleeding, or loss of body iron in the urine may be the cause.

A low level of iron in the body leads to impaired synthesis of hemoglobin. As a result, the hemoglobin content in erythrocytes decreases, and hypo­chromic microcytic anemia develops.

Iron deficiency is a decrease in iron content in serum and tissues manifested by clinical and laboratory signs.

Iron deficiency causes:

• inadequate iron intake;
• increased demand;
• malabsorption;
• increased loss.

Inadequate iron intake occurs due to nutritional deficiency. This is the most common cause of IDA in countries with low standards of living.

The increased need for iron develops during pregnancy, lactation, and rapid body growth during adolescence.

Malabsorption of iron is associated with the pathology of the small intestine (enteritis, tumors, enzyme deficiency) since iron is absorbed in the duodenum and ileum.