Efficacy of lithium in rheumatoid arthritis with granulocytopenia (felty's syndrome). A preliminary report.

Lithium carbonate was given orally for 6 weeks in varying doses to 10 patients with Felty's syndrome. All patients receiving 900 mg of lithium daily showed statistically significant elevations in granulocyte count during therapy. The effect was usually noted within a week and did not persist when the drug was withdrawn. The percentage increase in mean absolute granulocyte count varied between 138% and 617% of control value in different patients; the lower values were observed in those patients with basal serum lithium concentrations less than 0.5 mEq/liter. It is concluded that a consistent rise in peripheral blood granulocytes was achieved by lithium carbonate in a dosage of 900 mg daily in patients with Felty's syndrome.