Life-threatening thrombocytosis following GCSF treatment in a case of clozapine-induced agranulocytosis.

Clozapine was introduced in European market in 1972 as an effective treatment for schizophrenia without extrapyramidal side effects. Within a short while, the clozapine story virtually came to a halt following detection of life-threatening neutropenia and agranulocytosis. Judicial use of granulocyte colony stimulating factor (GCSF) can be life saving with infrequent side effects in these cases. Here we are presenting a case of clozapine induced agranulocytosis managed with GCSF but had transient but life-threatening thrombocytosis, a very uncommon complication of GCSF therapy. Expression of GCSF receptors on the surface of megakaryocytic lineage is thought to be the cause of this unusual phenomenon.