Fatigue in Idiopathic Erythrocytosis
Fatigue is not commonly reported or emphasized as a characteristic symptom in idiopathic erythrocytosis, which differs markedly from inflammatory conditions where fatigue is a dominant feature. The available literature on idiopathic erythrocytosis focuses primarily on thrombotic risk, disease progression, and hematologic parameters rather than symptom burden like fatigue 1, 2, 3.
Key Clinical Characteristics of Idiopathic Erythrocytosis
Idiopathic erythrocytosis is typically asymptomatic or minimally symptomatic in otherwise healthy adults:
- The condition is diagnosed in asymptomatic persons during routine screening, with an estimated frequency of 0.13% to 4.1% in general populations 1, 4.
- The primary clinical concerns are thrombotic complications and disease progression rather than constitutional symptoms 1, 2.
- After 5 years of follow-up in a large cohort study, patients with confirmed idiopathic erythrocytosis developed no hemorrhagic or thrombotic complications, suggesting a benign clinical course 1.
- Idiopathic erythrocytosis is characterized as a stable disease with low thrombotic risk and minimal tendency toward spontaneous progression 3.
Distinguishing Features from Polycythemia Vera
When fatigue is present in erythrocytosis, it should prompt consideration of polycythemia vera rather than idiopathic erythrocytosis:
- Patients with idiopathic erythrocytosis have normal spleen size, normal platelet counts, and no history of thrombosis at diagnosis—features that argue against polycythemia vera 2.
- The absence of splenomegaly and thrombotic events distinguishes idiopathic erythrocytosis from polycythemia vera, where these complications are more common 2.
- Idiopathic erythrocytosis patients have lower white blood cell and platelet counts compared to polycythemia vera patients 2.
When to Investigate Fatigue in Erythrocytosis Patients
If fatigue is prominent in a patient with erythrocytosis, investigate alternative causes rather than attributing it to the erythrocytosis itself:
- Consider hyperviscosity symptoms that may respond to phlebotomy, though phlebotomy in idiopathic erythrocytosis remains controversial 3.
- Evaluate for cardiovascular comorbidities, as aggressive control of cardiovascular risk factors is recommended in all erythrocytosis patients 4.
- Screen for secondary causes including cardiopulmonary disease, renal artery stenosis, EPO-secreting tumors, or medication effects (particularly sodium-glucose co-transporter-2 inhibitors and testosterone) 4.
- Assess for unrelated conditions that commonly cause fatigue in young adults, including thyroid dysfunction, nutritional deficiencies (iron, vitamin B12, vitamin D), sleep disturbances, and psychological factors 4.
Important Clinical Pitfall
Do not assume fatigue is a manifestation of low-grade idiopathic erythrocytosis—this symptom warrants investigation for other causes. The literature consistently describes idiopathic erythrocytosis as having minimal symptom burden, contrasting sharply with conditions like inflammatory rheumatic diseases where fatigue affects 50% of patients severely 2, 3.