Effects of the increased red cell mass

• 4 peripheral vascular resistance.

• 5 systemic O2 transport resulting in e.g. 5 cerebral blood flow and oxygen and glucose delivery to the brain.

• Thromboembolic complications also occur. Thus 'compensatory' erythrocytosis is a pathological rather than physiological condition.

Symptoms and signs are non-specific and those of the underlying cause (particularly if cardiac or pulmonary) may predominate. Pruritus, splenomegaly or the presence of leucocytosis or thrombocytosis suggest the alternative diagnosis of PV.

Investigation as listed under PV, notably RCM and plasma volume, arterial oxygen saturation, renal and hepatic function, urinalysis, serum erythro-poietin, renal ultrasound and if necessary abdominal CT.

The aim of therapy must be correction of the underlying cause where possible and reduction of the red cell mass. Venesection is the treatment of choice and if possible should be continued until a target Hct of <0.45 is achieved. In patients with cyanotic congenital heart disease, pulmonary disease or high O2-affinity haemoglobin, the extent of venesection can be determined by symptomatic response or by using the serum Epo level as a measure of tissue hypoxia. Induction of iron deficiency by chronic venesection assists control of erythrocytosis. Myelosuppressive therapy is not indicated.

0 0

Post a comment