Polycythemia, Spurious

Spurious polycythemia has many other names, including relative polycythemia, stress erythrocytosis, stress polycythemia, benign polycythemia, Gaisbock's syndrome, and pseudopolycythemia. Spurious polycythemia is characterized by increased hematocrit and normal or decreased red blood cell (RBC) total mass; it results from decreasing plasma volume and subsequent hemoconcentration. This disease usually affects middle-aged people and occurs more often in men than in women.

Causes

There are three possible causes of spurious polycythemia.

Dehydration

Conditions that promote severe fluid loss decrease plasma levels and lead to hemoconcentration. Such conditions include persistent vomiting or diarrhea, burns, adrenocortical insufficiency, aggressive diuretic therapy, decreased fluid intake, diabetic acidosis, and renal disease.

Hemoconcentration due to stress

Nervous stress leads to hemoconcentration by an unknown mechanism (possibly by temporarily decreasing circulating plasma volume or vascular redistribution of erythrocytes). This form of erythrocytosis (chronically elevated hematocrit) is particularly common in middle-aged men who are chronic smokers and have type A personalities (tense, hard-driving, anxious).

High-normal RBC mass and low-normal plasma volume

In many patients, an increased hematocrit merely reflects a normally high red cell mass and low plasma volume. This is particularly common in patients who are nonsmokers, are not obese, and have no history of hypertension.

Other factors that may be associated with spurious polycythemia include hypertension, thromboembolitic disease, elevated serum cholesterol and uric acid levels, and familial tendency.

Signs and symptoms

The patient with spurious polycythemia usually has no specific symptoms but may have vague complaints, such as headaches, dizziness, and fatigue. Less commonly, he may develop diaphoresis, dyspnea, and claudication.

Typically, the patient has a ruddy appearance, a short neck, slight hypertension, and a tendency to hypoventilate when recumbent. He shows no associated hepatosplenomegaly but may have cardiac or pulmonary disease.

Diagnosis

Hemoglobin and hematocrit levels and RBC count are elevated; RBC mass, arterial oxygen saturation, and bone marrow are normal. Plasma volume may be decreased or normal. Hypercholesterolemia, hyperlipidemia, or hyperuricemia may be present.

Spurious polycythemia is distinguishable from polycythemia vera by its characteristic normal RBC mass, elevated hematocrit, and absence of leukocytosis.

Treatment

The principal goals of treatment are to correct dehydration and to prevent life­threatening thromboembolism. Rehydration with appropriate fluids and electrolytes is the primary therapy for spurious polycythemia secondary to dehydration. Therapy must also include appropriate measures to prevent continuing fluid loss.