Clozapine associated thrombocytopenia
A woman aged 22, suffering from paranoid schizophrenia (as diagnosed by DSM-IV) for the past three years, presented with an acute episode. She had received adequate trials of olanzapine, risperidone and quetiapine along with electroconvulsive therapy. There was history of severe extrapyramidal side effects with risperidone. Taking this into account she was started on clozapine. Prior to starting of clozapine her hemogram including platelet count did not reveal any abnormality. For the management of acute symptoms in view of the suicidal risk, she was treated with electroconvulsive therapy, lorazepam up to 4 mg/day and was started on clozapine and the dose was gradually increased to 187.5 mg/day over the period of four weeks because of side effects of hypersalivation and constipation. While clozapine was increased, leucocyte count and platelet counts were monitored regularly on weekly basis and serial monitoring did not reveal any abnormality. With this she achieved symptomatic remission following which lorazepam was stopped. While on clozapine 187.5 mg/day, low platelet count (101,000 and 98,000/μL on two occasions) was noted for the first time after 17 weeks of continuation of clozapine at the above said dose without reduction in the leucocyte count or haemoglobin levels. Following this monitoring was increased and platelet count kept on fluctuating between 1,20,000/μL to 1,35,000/μL. Over the period, platelet count started dropping. By another 24 weeks of clozapine therapy, the platelet count dropped to 60,000/μL without any reduction in the leucocyte count and the haemoglobin levels. The drop occurred despite reduction in the dose of clozapine upto 125 mg/day. Clozapine was stopped completely as a result. Throughout this period she never had any fever, skin rash, purpura, excessive menstrual bleeding or bleeding from any other source, arthritis, arthralgia, muscle pain and muscle weakness. Her investigations in the form of serum electrolytes, liver function test, renal function test, prothrombin time, bleeding time, clotting time and ultrasound abdomen and pelvis did not reveal any abnormality. She was also evaluated by physician and the opinion was that the low platelet count may be related to clozapine.\nWithin a week of stopping clozapine platelet counts started improving and by six weeks her platelet count was 1,80,000/μL. In the meanwhile, with stoppage of clozapine, she had relapse of symptoms and required inpatient care, was treated with electroconvulsive therapy, lorazepam and chlorpromazine, with which she achieved remission. During this period her platelet count remained within the normal range.