What are the most common symptoms of secondary erythrocytosis?

Symptoms of Secondary Erythrocytosis

The most common symptoms of secondary erythrocytosis are hyperviscosity symptoms, which include headache, faintness, dizziness, fatigue, tinnitus, blurred vision, paraesthesia of fingers, toes, and lips, muscle pain, and weakness. 1

Understanding Secondary Erythrocytosis

Secondary erythrocytosis is a physiological increase in red blood cell mass in response to hypoxemia, which differs from polycythemia vera (a neoplastic proliferation of hematopoietic cells). This condition occurs when the body attempts to compensate for chronic hypoxemia by increasing red blood cell production through erythropoietin stimulation 1.

Pathophysiology

• Results from external stimuli to the bone marrow leading to excess red cell production 2
• Causes include chronic hypoxemia from cyanotic congenital heart disease, pulmonary disease, or high altitude
• Leads to increased blood viscosity directly related to red blood cell mass 1

Symptom Presentation

Hyperviscosity Symptoms

• Headache - often the earliest and most common complaint
• Dizziness and faintness - due to cerebral blood flow alterations
• Fatigue - despite increased oxygen-carrying capacity
• Tinnitus - ringing in the ears
• Blurred vision - from retinal blood flow changes
• Paraesthesia of fingers, toes, and lips
• Muscle pain and weakness

These symptoms are typically classified as moderate when they interfere with some activities, and severe when they interfere with most activities 1.

Important Clinical Considerations

1. Hyperviscosity symptoms are unlikely in iron-replete patients with hematocrit < 65% 1
2. The severity and frequency of hyperviscosity symptoms do not always correlate with measured hematocrit 1
3. Symptoms may mimic those of iron deficiency, which can coexist with erythrocytosis 1

Complications of Secondary Erythrocytosis

Secondary erythrocytosis can lead to several complications:

• Bleeding diathesis - despite increased red cell mass, patients may experience bleeding due to abnormalities in platelets (thrombocytopenia and thrombasthenia) and coagulation pathways 1
• Thrombotic events - paradoxically, patients are also at risk for thrombosis 1
• Cerebrovascular accidents - can be caused by thrombo-embolic events, rheological factors, or endothelial dysfunction 1
• Renal dysfunction - chronic cyanosis can lead to abnormal glomeruli 1
• Hyperuricemia - due to increased turnover of red blood cells and impaired urate filtration 1

Management Considerations

When evaluating a patient with suspected secondary erythrocytosis:

1. Hydration status should be assessed first, as dehydration can exacerbate symptoms 1
2. Iron deficiency should be evaluated, as it can mimic hyperviscosity symptoms 1
3. Therapeutic phlebotomy should only be performed in the presence of moderate/severe hyperviscosity symptoms with hematocrit > 65% and in the absence of dehydration or iron deficiency 1
4. Routine phlebotomies are not recommended due to risk of iron depletion, decreased oxygen-carrying capacity, and stroke 1

Monitoring Recommendations

For patients with secondary erythrocytosis:

• Regular assessment of oxygen saturation
• Monitoring of exercise capacity
• Blood work including complete blood count, mean corpuscular volume, serum ferritin, iron studies
• Assessment for symptoms of hyperviscosity

By recognizing and appropriately managing the symptoms of secondary erythrocytosis, clinicians can help improve quality of life and prevent complications in affected patients.