Management of Elevated Blood Counts on Fasting Labs

Diagnostic Approach

The European Hematology Association recommends continuing daily aspirin in suspected myeloproliferative disorders to reduce thrombotic risk 1
A non-fasting CBC with differential is essential to distinguish true polycythemia from relative polycythemia caused by dehydration or hemoconcentration during fasting, and the American Society of Hematology suggests this as a first step 1
JAK2 V617F mutation testing is present in >95% of polycythemia vera cases, according to the National Comprehensive Cancer Network 1
Serum erythropoietin level is typically low or low-normal in polycythemia vera, as stated by the European Hematology Association 1
Bone marrow biopsy with cytogenetic analysis is recommended if diagnosis remains unclear after initial testing, as suggested by the American Society of Hematology 1

Infection should be ruled out with appropriate cultures if clinically indicated, as recommended by the Infectious Diseases Society of America 2
Medications that can cause leukocytosis, such as corticosteroids and growth factors, should be reviewed, according to the National Comprehensive Cancer Network 3

Aspirin should be continued unless contraindicated, as recommended by the European Hematology Association, to prevent thrombotic complications in myeloproliferative disorders 1
If non-fasting CBC remains elevated, proceed urgently with JAK2 mutation testing and erythropoietin level, as suggested by the American Society of Hematology 1
Maintain aspirin 81-100 mg daily, as recommended by the European Hematology Association, in patients with elevated blood counts 1
Refer to hematology for definitive diagnosis and management, as suggested by the National Comprehensive Cancer Network, if non-fasting CBC remains elevated 1