Pediatric Polycythemia Workup

Updated: Jun 13, 2023
  • Author: May C Chien, MD; Chief Editor: Lawrence C Wolfe, MD  more...
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Laboratory Studies

The following laboratory findings can be seen in polycythemia. The reference range values for the clinician's laboratory findings in polycythemia should be cross-correlated.

  • Complete blood count (CBC): Leukocytosis and thrombocytosis are commonly observed but not universal in patients with polycythemia. Leukocytes are greater than 12 X 10 9/L; platelets are greater than 400 X 10 9/L. Large platelets are often observed. Platelets can be morphologically and qualitatively abnormal. Red cell mass is greater than 36 mL/kg in men and greater than 32 mL/kg in women. RBCs often have anisocytosis, basophilic stippling, and polychromatophilia.
  • Serum erythropoietin (Epo): Elevated serum Epo levels can be used to distinguish polycythemia vera (PV) from secondary polycythemia. Elevated Epo levels are observed in secondary polycythemia. Low Epo levels suggest primary familial and congenital polycythemia (PFCP) or polycythemia vera, but Epo levels may be normal.
  • Elevated sedimentation rate
  • Spurious hyperkalemia or hypokalemia
  • Increased blood viscosity
  • Artifactual prolongation of coagulation studies

The following laboratory findings and tests can be helpful in determining the etiology of polycythemia:

  • Gene testing: Screen for EPOR mutation and JAK2 mutation if primary polycythemia is suspected
  • Molecular analysis: Consider molecular analysis of the VHL gene
  • Oxygen dissociation curves and hemoglobin electrophoresis can be used to assess for high–oxygen-affinity mutants and 2,3-disphosphoglycerate (2,3-DPG) deficiency
  • Urinalysis can reveal microscopic hematuria, a sign of renal disease
  • Elevated serum glucose and hypokalemia can suggest functioning endocrine tumors
  • Liver panel abnormalities can suggest the presence of liver disease
  • Co-oximetry should be performed in all patients in whom CO poisoning or congenital methemoglobinemia is suspected
  • P 50, or the oxygen partial pressure at which hemoglobin is 50% saturated with oxygen, is reduced in high-affinity hemoglobins

A study by Cacemiro et al indicated that compared with patients with polycythemia vera, those with secondary polycythemia have lower plasma levels of the cytokines interleukin-17A (IL-17A), interferon-γ (INF-γ), IL-12p70, and tumor necrosis factor-α (TNF-α). Consequently, the investigators suggested that the cytokine production profile of secondary polycythemia may be useful in distinguishing that disease from polycythemia vera. [34]


Imaging Studies

The following imaging studies can be helpful in determining the etiology of polycythemia:

  • Abdominal ultrasonography is helpful in excluding underlying renal and hepatic pathology
  • Chest radiographs may provide clues to pulmonary or cardiac etiologies to polycythemia
  • Computed tomography (CT) scanning of the chest, abdomen, pelvis, or head is helpful to evaluate for tumors, cancer, or other pathology

Other Tests

The need for bone marrow biopsy is still controversial. Biopsy is not a part of the diagnostic criteria. It may be helpful when trying to differentiate polycythemia vera from other myeloproliferative disorders and to assess the degree of fibrosis.

Cytogenetics are not routinely performed but should be used if the diagnosis is questionable and if the differential includes malignancy, myelodysplastic syndrome, or other myeloproliferative disorders.


Histologic Findings

If a bone marrow biopsy is performed, the marrow in polycythemia vera is typically hypercellular, including all marrow elements and displaced marrow fat. The number of megakaryocytes is usually increased with wide variation in size.  Stainable iron is decreased or absent, and, later in the disease course, fibrosis and marrow reticulin fibers are increased. [35]