From the Guidelines
For a 65-year-old male smoker with hemoglobin of 174 g/L and MCV of 99 fL, I recommend a comprehensive workup for polycythemia and smoking-related conditions. Initial investigations should include complete blood count with differential, peripheral blood smear, serum ferritin, iron studies, erythropoietin level, JAK2 V617F mutation testing, and arterial blood gases 1. Additional tests should include renal and liver function tests, chest X-ray, pulmonary function tests, and abdominal ultrasound focusing on the liver and spleen. The elevated hemoglobin suggests polycythemia, which could be primary (polycythemia vera) or secondary to chronic hypoxia from smoking-related lung disease. The slightly elevated MCV (normal range typically 80-96 fL) may indicate early B12 or folate deficiency, alcohol use, or can be associated with smoking. Oxygen saturation should be measured to assess for hypoxemia. If polycythemia vera is suspected based on initial results, bone marrow biopsy may be necessary for definitive diagnosis. Smoking cessation counseling should be initiated immediately as this is likely contributing to the patient's condition regardless of the underlying cause 1. It is essential to prioritize the patient's morbidity, mortality, and quality of life when determining the best course of action for their condition. Some studies, such as 1, provide guidance on the diagnosis and management of diabetes, but they are not directly relevant to this patient's condition. Therefore, they should not influence the decision-making process for this patient's care. The most critical factor in this patient's management is addressing the potential underlying causes of their polycythemia and smoking-related conditions. By prioritizing these factors and initiating a comprehensive workup, we can improve the patient's outcomes and quality of life. Key considerations in the patient's management include:
- Complete blood count with differential
- Peripheral blood smear
- Serum ferritin
- Iron studies
- Erythropoietin level
- JAK2 V617F mutation testing
- Arterial blood gases
- Renal and liver function tests
- Chest X-ray
- Pulmonary function tests
- Abdominal ultrasound
- Oxygen saturation measurement
- Smoking cessation counseling.
From the Research
Initial Assessment
The patient is a 65-year-old male who is a smoker, with a hemoglobin (Hb) level of 174 g/L and a mean corpuscular volume (MCV) of 99 fL. These values indicate erythrocytosis, which can be primary (such as polycythemia vera) or secondary to other causes.
Diagnostic Considerations
To differentiate between primary and secondary erythrocytosis, several investigations should be considered:
- Serum Erythropoietin (EPO) Level: Although a low EPO level is often associated with polycythemia vera (PV), elevated EPO levels do not exclude this diagnosis 2, 3. EPO levels can be influenced by factors such as smoking and obesity, making it less reliable as a standalone diagnostic marker 4.
- JAK2 Mutation Test: The presence of the JAK2 V617F mutation is a major diagnostic criterion for PV. Testing for this mutation can help distinguish PV from secondary erythrocytosis 2, 3, 4.
- Bone Marrow Biopsy: This can provide definitive evidence of a clonal marrow population, supporting a diagnosis of PV 2, 5.
- Other Investigations: These may include tests to rule out secondary causes of erythrocytosis, such as hypoxemia, renal or hepatic pathology, and other myeloproliferative disorders 5.
Investigation Plan
Based on the patient's presentation, the following investigations are recommended:
- Serum EPO level
- JAK2 mutation test
- Bone marrow biopsy
- Complete blood count with differential and platelet count
- Reticulocyte count
- Blood smear examination
- Tests to rule out secondary causes of erythrocytosis, such as arterial blood gas, renal function tests, and liver function tests
- Imaging studies, such as ultrasound or CT scan, to evaluate for splenomegaly or other abnormalities
These investigations will help establish a definitive diagnosis and guide further management. It is essential to consider the patient's smoking status and potential comorbidities when interpreting the results of these investigations 4.