Leukopenia: Idiopathic or Drug-Induced — How to Differentiate?

To the Editor: In the case report presented in the letter by Gavras and Gavras (February 25 issue) a total white-cell count fluctuated spontaneously from 3200 to 7500 per cubic millimeter, making it difficult to differentiate between drug-induced or idiopathic leukopenia and normal variation.¹ This kind of fluctuation is probably more common than is appreciated, since it has already been noted in normal subjects² and in subjects with benign familial leukopenia.³ However, since most white-cell counts are performed in the morning or scheduled too infrequently to indicate changes that occur within a day, many of these fluctuations are missed.² On.