Risk factors for reduction in white blood cell count:
(1) child or adolescent (younger age)
(2) male gender
(3) African American (Black)
(4) presence of other causes for neutropenia
There are 2 basic patterns of reduce white blood cell count:
(1) a mild to moderate neutropenia
(2) an agranulocytosis (in 1-2% of patients) that may be associated with fatal infection
Patients being treated with clozapine should undergo monitoring of their CBC. If a decline in neutrophils occurs (absolute count below 1,500 per µL) then therapy is stopped and the patient evaluated.
Therapy with clozapine may be restarted if:
(1) there is no other treatment alternative
(2) there is another explanation for the neutropenia that can be corrected
(3) the neutropenia was mild to moderate and reverses on discontinuation.
Some patients who are restarted on clozapine may be treated with a granulocyte colony stimulating agent (Neupogen, other) and/or lithium carbonate, both of which cause leukocytosis.
On the other hand, therapy is not restarted if:
(1) the patient develops agranulocytosis
(2) clozapine is implicated as the cause for the neutropenia
(3) recovery from neutropenia is slow
