American Board of Internal Medicine (ABIM) Certification Practice Exam

How is Polycythemia Vera diagnosed?

1. Bone marrow biopsy

2. Determination of serum erythropoietin level and JAK2

3. Complete blood count only

4. Gene mutation analysis for BCR-ABL

The correct answer is: Determination of serum erythropoietin level and JAK2

Polycythemia Vera (PV) is primarily diagnosed through the identification of a JAK2 mutation, along with the assessment of serum erythropoietin levels. The majority of patients with PV exhibit a JAK2 V617F mutation, which is a key genetic marker for this condition. Elevated red blood cell mass is characteristic of PV, but the diagnosis requires combining hematological findings with these specific testing metrics. While measuring serum erythropoietin levels can help distinguish PV from secondary causes of polycythemia, such as hypoxia or tumors producing erythropoietin, the presence of low levels of erythropoietin is consistent with PV, as the disease is generally associated with autonomous erythrocyte production that doesn't rely on this hormone. The other options provided, while relevant in the context of hematological disorders, do not specifically align with the standard diagnostic criteria for PV. Although a bone marrow biopsy can provide additional information, especially if the diagnosis is uncertain, it is not the primary method used for diagnosing PV. Similarly, a complete blood count is useful for initial assessment of elevated red blood cell levels but is insufficient alone for a definitive diagnosis. Gene mutation analysis for BCR-ABL is more pertinent to Acute My