To determine the prevalence and clinical significance of
leukocytosis in
rheumatoid arthritis (RA), records of 98 consecutive outpatients with this disease were reviewed.
Leukocytosis, defined
as 2 or more white blood cell counts (WBC) greater than 10,000/mm, was found in 27%. Among patients currently receiving
steroid therapy (mean dose
prednisone 7 mg daily), the prevalence was 40%; in all others, the prevalence was 7.5%. The WBC elevation was primarily caused by an increase in neutrophils. Patients with
leukocytosis tended to have more active
arthritis, but there were no differences in extra-articular manifestations or
drug therapy except for the use of
corticosteroids.A review of the literature confirms the contributions of both disease activity and
steroid therapy to WBC elevation. There is little published information on the effect of chronic, low dose
corticosteroids on WBC counts, but our study suggests that this is an important factor in
leukocytosis in RA.Newly detected
leukocytosis in RA should alert the physician to the possibility of occult
infection. In the absence of suggestive signs and symptoms, an infectious cause is seldom found, but, despite the few
infections found in this series, continuing vigilance is recommended.