Evaluation of Mildly Elevated Red and White Blood Cell Counts

Red Blood Cell Elevation

The American College of Physicians recommends assessing clinical signs of dehydration, such as reviewing fluid intake history and recent losses, to determine if dehydration is the cause of elevated hematocrit, with a strength of evidence of high 1
Normal hemoglobin values for postmenopausal females are 15.5 ± 2.0 g/dL with hematocrit 47 ± 6%, according to the National Kidney Foundation 2
The European Hematology Association suggests ordering JAK2V617F mutation testing as first-line if polycythemia vera is suspected, followed by JAK2 exon 12 mutation if negative, with a strength of evidence of moderate 3
Polycythemia vera diagnostic criteria require hemoglobin >16.5 g/dL in women OR evidence of increased red cell volume, PLUS presence of JAK2 mutation, as recommended by the International Society for Hematology 3

The Infectious Diseases Society of America recommends obtaining manual differential to assess band forms and immature cells, as automated differentials may miss critical findings, with a strength of evidence of high 4, 5
Elevated total band count (>1500 cells/mm³) has the highest likelihood ratio (14.5) for detecting bacterial infection, even without fever, according to the Centers for Disease Control and Prevention 4, 5
Left shift (≥6% band neutrophils) has likelihood ratio of 4.7 for bacterial infection, as reported by the American Society for Clinical Pathology 4, 5

The American Society of Hematology recommends referring to hematology/oncology immediately if abnormalities in other cell lines (thrombocytopenia, anemia) suggesting multiple cytopenias are present, with a strength of evidence of high 6
Lymphadenopathy or splenomegaly on examination requires immediate referral to hematology/oncology, as recommended by the European Hematology Association 6