Polycythemia rubra vera and artifactual hypoglycemia

Area of Science:

• Hematology
• Clinical Biochemistry

Background:

• Polycythemia vera is a myeloproliferative neoplasm characterized by increased red blood cell mass.
• Extreme leukocytosis can lead to unusual metabolic phenomena.
• Artifactual hypoglycemia is a laboratory error mimicking true hypoglycemia.

Observation:

• A patient with polycythemia vera presented with marked leukocytosis (55,000–86,000/cu mm).
• The patient exhibited significantly low serum glucose levels (as low as 8 mg/dL).
• Despite the low glucose readings, the patient remained asymptomatic.

Findings:

• Investigation revealed the hypoglycemia was artifactual, not clinical.
• Excessive glucose consumption by white blood cells (WBCs) in the blood sample caused the artifact.
• This phenomenon, previously noted in other leukemic states, is described here for polycythemia vera.

Implications:

• This case expands the known causes of artifactual hypoglycemia.
• Extreme leukocytosis, irrespective of the underlying condition, can cause this artifact.
• Recognizing this artifact can prevent unnecessary diagnostic workups for hypoglycemia in patients with high WBC counts.