POLYCYTHEMIA

Polycythemia denotes increase in total red cell mass and Hb levels above the age-related norms, excluding pseudo­polycythemia, i.e. hemoconcentration in dehydration, etc. True polycythemia is characterized by increases in both-the RBC volume and the blood volume.

WHO defines polycythemia as Hb gt;16.5 gm/dl (gt;16 gm/dl in females) or hematocrit gt;49% ( gt;48% in females) or red cell mass gt;25% above the mean predicted value, in adults.

In children, symptomatic cases with Hb gt;16 gm/dl or Hematocrit gt;45 beyond neonatal period are considered as polycythemic for practical purpose, who need investigations.

Etiology: Polycythemia in children is rarely primary (polycythemia vera) and generally indicates excessive erythropoiesis due to persistent hypoxic states or erythropoietin-secreting tumors (Table 19.15).

TABLE 19.15: Causes of polycythemia

• Secondary (common)

- Neonates:

#9830; Delayed clamping of umblical cord

#9830; Infant of diabetic mother

#9830; Twin-twin transfusion

- Chronic hypoxia:

#9830; High altitude

#9830; Chronic lung disease, cyanotic CHDs

#9830; Hb'pathies: Methemoglobinemia, CO poisoning

- Excess erythropoietin (EPO) activity:

#9830; Chronic renal disease

#9830; EPO secreting tumors: Hepatic, renal, adrenal

- Others: Cushing syndrome, anabolic steroids

• Primary (rare)

- Polycythemia vera

- Benign familial polycythemia

CO: Carbon monoxide

Clinical presentation depends on severity and duration of hematological abnormality and include:

• Flushing of skin and mucus membranes,

• Thromboembolic episodes due to blood hyperviscosity,

• Cyanosis and clubbing in severe or chronic cases,

• Iron deficiency due to increased erythropoiesis.

• Features of primary disease.

Management: While severe cases of polycythemia may require periodic phlebotomy, most cases can be managed with exchange transfusion, treatment of primary cause and iron supplementation.

19.8