From the Guidelines
A medical workup for a patient with elevated red blood cells (RBCs), hemoglobin, and hematocrit (HCT) should begin with a thorough history and physical examination, followed by targeted laboratory testing to determine the underlying cause, with a focus on reducing the risk of thrombotic events and improving quality of life. The initial evaluation should include a complete blood count with differential, peripheral blood smear, serum erythropoietin level, arterial blood gas analysis, and iron studies 1. Additional testing should include JAK2 V617F mutation analysis, renal and liver function tests, and pulse oximetry to assess oxygen saturation. If primary polycythemia (polycythemia vera) is suspected, bone marrow biopsy may be necessary for definitive diagnosis, as recommended by the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of Philadelphia chromosome-negative chronic myeloproliferative neoplasms 1.
Some key points to consider in the workup include:
- Measuring P50 (oxygen pressure at 50% hemoglobin-oxygen saturation) if family history suggests a congenital cause 1
- Investigating secondary causes through chest imaging, sleep studies for sleep apnea, and abdominal ultrasound to evaluate for renal or hepatic pathology
- Assessing for the use of androgen preparations and EPO doping, as these can contribute to elevated RBCs, hemoglobin, and HCT 1
- Considering the balance between the physiological benefit of an increased hematocrit level and the possible impairment of oxygen delivery to tissues as a result of increased whole blood viscosity 1
Treatment should focus on reducing the risk of thrombotic events, improving quality of life, and managing the underlying cause, with therapeutic phlebotomy to maintain hematocrit below 45%, hydration, and low-dose aspirin (81-100mg daily) as potential components of the treatment plan. The goal of treatment is to reduce the risk of occurrence and recurrence of thrombosis, as well as to reduce the risk of evolution to myelofibrosis, myelodysplastic syndrome, and/or acute myeloid leukemia 1. By prioritizing the reduction of thrombotic risk and improving quality of life, the treatment plan can be tailored to the individual patient's needs and underlying cause of their elevated RBCs, hemoglobin, and HCT.
From the Research
Medical Workup for Elevated RBCs, Hemoglobin, and HCT
The medical workup for a patient with elevated red blood cells (RBCs), hemoglobin, and hematocrit (HCT) involves several steps to determine the underlying cause of these abnormalities.
- Initial Evaluation: The initial evaluation should include a complete medical history, physical examination, and laboratory tests to rule out secondary causes of erythrocytosis, such as tobacco smoking or sleep apnea 2, 3.
- Laboratory Tests: Laboratory tests should include a complete blood count (CBC) with differential, erythropoietin level, and JAK2 mutation testing to diagnose polycythemia vera (PV) 2, 3.
- Diagnostic Criteria: The World Health Organization (WHO) diagnostic criteria for PV include a hemoglobin level greater than 16.5 g/dL in men or 16.0 g/dL in women, and a hematocrit greater than 49% in men or 48% in women 4.
- Bone Marrow Morphology: Bone marrow morphology can be useful in diagnosing PV and assessing disease progression 5.
- Clinical Parameters: Clinical parameters such as age, smoking history, and body mass index (BMI) can help distinguish between PV and secondary erythrocytosis (SE) 5.
- Vascular Function and Structure: Elevated HCT, hemoglobin, and RBCs have been associated with vascular function and structure, and may increase the risk of cardiovascular disease 6.
Possible Diagnostic Algorithm
A possible diagnostic algorithm for PV includes:
- Step 1: Evaluate clinical and laboratory parameters to determine the likelihood of PV.
- Step 2: Perform JAK2 mutation testing and bone marrow morphology to confirm the diagnosis.
- Step 3: Assess vascular function and structure to determine the risk of cardiovascular disease.
- Step 4: Develop a treatment plan based on the diagnosis and risk assessment, which may include therapeutic phlebotomy, aspirin, and cytoreductive therapy 2, 3.