Policitemias - Consequências e tratamento

Consequências

O quadro clínico das policitemias ou poliglobulias está relacionado com a hiperviscosidade sanguínea, devido ao aumento da massa globular. É frequente o quadro de oclusão vascular (tromboses, IAM, AVE, etc.) como complicação da doença, relacionado com o aumento do volume ou da massa globular.

A viscosidade sanguínea é consequente ao aumento da massa globular, que reflete aumento dos glóbulos vermelhos. Devido à hiperviscosidade, além dos fenômenos tromboembólicos, a doença apresenta sintomas não específicos, como dificuldade circulatória periférica, cefaleia, fraqueza, tontura, sonolência, falta de memória, perda de peso, sudorese noturna, prurido e sangramentos leves, como perda sanguínea nasal.

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The risks associated with erythrocytosis (hyperviscosity, thrombosis, impaired hemostasis) begin to increase substantially as the hematocrit moves into the 55% to 60% range. When the condition cannot be treated etiologically in prompt fashion, phlebotomy should be performed. Phlebotomy improves oxygen delivery, relieves hyperviscosity symptoms, and prevents the thromboembolic and hemorrhagic complications of polycythemia. The target hematocrit is in the low to middle 40s, the level at which tissue oxygenation is optimal in normovolemic patients. Phlebotomy is especially useful in patients with polycythemia vera and pathologic secondary erythrocytosis. Even in cases in which the increase in red cell mass represents a physiologic accommodation to chronic hypoxemia, phlebotomy may be indicated if the erythrocytosis becomes excessive (hematocrit >60%) and threatens oxygen delivery. Reducing the hematocrit to less than 55% improves exercise tolerance in patients with severe chronic obstructive pulmonary disease.

Phlebotomy is conducted by removing up to 500 mL of blood as often as every 2 to 3 days to achieve a hematocrit of less than 55%. For patients who cannot tolerate such large losses of volume (e.g., the elderly), phlebotomy is limited to removal of no more than 250 mL once or twice a week. Iron deficiency may ensue but should not be corrected in cases of polycythemia vera or pathologic secondary erythrocytosis because such treatment may stimulate a fulminant recurrence of red cell production. In patients with cardiopulmonary disease, a modest amount of iron replacement to correct microcytosis is probably beneficial because microcytic erythrocytes increase blood viscosity and decrease oxygen delivery. The severely erythrocytic patient who is to undergo surgery requires phlebotomy to prevent compromised hemostasis. Preoperative phlebotomy should be followed by the administration of a volume expander to correct volume depletion.

Tratamento

Secundária – Corrigir a causa base;

Policitemia vera – sangrias (casos leves pouco sintomáticos e abaixo de 50 anos) 400 mL a 450 mL de sangue a cada 7 dias até que o hematócrito fique em torno de 40% ou sangrias menores de 150 a 300 mL, a cada 5 dias, com retransfusão da parte plasmática. A periodicidade do procedimento, em geral, é de 3 meses.
Fósforo radioativo – contra melhor a doença;
Busulfan (2 a 4 mg/dia) e hidroxiuréia (500 a 1000mg/dia)
Avaliação hematológica durante o tratamento

Referências

Goroll, Allan H. II. Mulley, Albert G. Primary Care Medicine: Office Evaluation and Management of the Adult Patient - Evaluation of Erythrocytosis (Polycythemia). Lippincott Williams & Wilkins, 6th Edition: 2009

Hematologia e hemoterapia: fundamentos de morfologia, fisiologia e patologia clínica. Therezinha Verrastro e cols. São Paulo: Editora Atheneu, 2005.