Quetiapine and Leukopenia

Ms. A was a 23-year-old Caucasian woman who had been diagnosed with schizoaffective disorder, bipolar type, without prior medical conditions, who had been residing on an inpatient psychiatric ward for about 3 months. She exhibited auditory hallucinations and bizarre somatic delusions. During prior admissions, she had received the following psychotropic drugs: diphenhydramine, trazodone, perphenazine, risperidone, olanzapine, lithium, bupropion, fluoxetine, and droperidol. Risperidone therapy, 1 mg b.i.d., was initially started, but after 5 days of therapy, Ms. A claimed that it made her “hyper and sedated.” Quetiapine treatment was instituted and slowly titrated, beginning with 50 mg/day. Her highest dose was 600 mg/day at the end of 3 months. During this hospital stay, Ms. A had refused all laboratory tests on the basis of her bizarre somatic delusions. She was prescribed valproic acid, 1000 mg/day, which she had received for years; her concurrent CBC results then fell within normal limits.

As Ms. A’s psychosis cleared, after she had reached a dose of 600 mg/day of quetiapine, she agreed to have blood tests performed. All laboratory results were normal except the CBC. Her WBC count was 2800 cells/mm³, her absolute neutrophil count was 900 cells/mm³, and her other cell counts were within normal ranges. An HIV test produced negative results. Her valproic acid level was 86 mg/liter. Quetiapine was discontinued, and 12 days later, Ms. A’s WBC count was 2800 cells/mm³, and her absolute neutrophil count was 1000 cells/mm³. Three days later, her WBC count was 2900 cells/mm³, and her absolute neutrophil count was 1000 cells/mm³. These values slowly rose to normal ranges over the next 3 months. Olanzapine therapy was begun 9 days after quetiapine therapy was discontinued.

Twenty-two days after she discontinued quetiapine, Ms. A’s WBC count was 4000 cells/mm³, and her absolute neutrophil count was 1700 cells/mm³. Over the next 15 weeks, three CBCs revealed WBC counts ranging from 4000 to 4700 cells/mm³; her absolute neutrophil count was 1600–2200 cells/mm³. A WBC count of 3300 cells/mm³ with an absolute neutrophil count of 1200 cells/mm³ 30 days after quetiapine therapy was discontinued was the only exception. Three months before this admission, Ms. A’s baseline WBC count had been 5800 cells/mm³. One day before admission, her WBC count was 5600 cells/mm³.