What does a white blood cell (WBC) count of 6.2 indicate in an adult patient?

Normal White Blood Cell Count

A WBC count of 6.2 × 10⁹/L is completely normal and requires no further evaluation or intervention in an asymptomatic adult patient. 1, 2

Reference Range Context

• The normal WBC range for adults is approximately 4.0-11.0 × 10⁹/L, placing a count of 6.2 well within the middle of the normal distribution 3, 1
• Population studies of healthy 75-year-olds show median WBC counts of 6.3 × 10⁹/L in men and 5.7 × 10⁹/L in women, confirming that 6.2 represents a typical baseline value 2

Clinical Significance

This WBC count does not meet any threshold for concern regarding infection or other pathology:

• Leukocytosis requiring evaluation for bacterial infection is defined as WBC ≥14,000 cells/mm³ (14.0 × 10⁹/L), which is more than double this patient's value 3, 1
• The Infectious Diseases Society of America explicitly states that in the absence of leukocytosis (WBC <14,000), left shift, fever, or specific clinical manifestations of focal infection, additional diagnostic tests are not indicated due to low potential yield 3, 1

When Further Evaluation Would Be Needed

Do not order additional testing unless the patient develops:

• Fever >38°C or hypothermia <36°C 4
• Specific symptoms suggesting focal infection (dysuria, productive cough, localized pain, altered mental status) 3, 1
• Hemodynamic instability (hypotension, tachycardia, tachypnea) 4

Important Caveats

• If a complete blood count with differential was performed, verify that the differential is also normal—specifically that there is no left shift (band neutrophils <16% and absolute band count <1,500 cells/mm³), as left shift can indicate bacterial infection even with normal total WBC 1, 5
• A manual differential count is essential if infection is suspected clinically, as automated analyzers are insufficient for detecting subtle left shifts 1, 4
• Do not confuse this normal value with the specialized context of acute promyelocytic leukemia risk stratification, where WBC >10 × 10⁹/L defines high-risk disease—this patient's count is well below that threshold and APL classification is irrelevant without other hematologic abnormalities 3