Methylprednisolone-Induced Lymphocytosis in Patients with Immune-Mediated Inflammatory Disorders.

BACKGROUND: Transient acute reversible lymphopenia occurring within hours after glucocorticoid administration is a well-known phenomenon. The objective of this study was to establish the impact of chronic methylprednisolone (mPDN) administration on lymphocyte counts in patients with immune-mediated inflammatory disorders.

METHODS: The charts of 44 women and 17 men (median age, 59 years) with several immune-mediated inflammatory disorders receiving oral mPDN for at least 4 months were reviewed. Morning lymphocyte counts measured during treatment (LP) were compared with pretreatment values (LA). In addition, the acute effect of mPDN on lymphocyte counts was evaluated in 43 of these patients by quantifying lymphocyte subpopulations before and 8 hours after mPDN administration. Values are expressed as median with 25%-75% interquartile range.

RESULTS: The initial daily oral mPDN dose was 28 mg (12-32 mg). An increase in morning lymphocyte counts was detected 13 days (8.5-16 days) after initiation of mPDN treatment (LP: 2130/μL vs LA: 1650/μL; P = .0121) and persisted over time. Morning lymphocytosis (LP ≥4000/μL) was observed in 15 patients, including 7 with hyperlymphocytosis (LP ≥5000/μL). The increase in morning lymphocyte counts during treatment was most marked for CD4 T cells. In the subset of patients who agreed to a second blood test after mPDN absorption, a 49% decrease in the lymphocyte count (P <.0001) was transiently observed at the 8-hour time point.

CONCLUSIONS: A significant increase of the morning lymphocyte count is frequently observed in patients with immune-mediated inflammatory disorders chronically treated with oral mPDN. Heightened awareness that the timing of blood sampling in corticosteroid-treated patients affects lymphocyte counts, with possible hyperlymphocytosis before absorption, should help avoid unnecessary investigations and worry.