The potential hematotoxic effects of antipsychotic drugs are well known and may limit the use of some effective therapies. Although some previous studies have suggested that patients with schizophrenia may have altered "normal" values, only limited data were available. It is now believed that biological values do not usually follow a normal distribution; therefore, reference ranges are frequently used when interpreting laboratory tests in clinical practice and in research. However, it may be important to use disease-specific hematologic reference ranges when evaluating laboratory test results for patients with schizophrenia. In this study, data taken from patients with schizophrenia prior to treatment in previous phase II and phase III pharmaceutical studies were analyzed to produce reference ranges for a variety of hematologic parameters. An increased variability was shown in the reference ranges for all white blood cell indices between patients with schizophrenia and the population without schizophrenia. Certain reference values also showed heterogeneity for gender, age, and racial descent. This study suggests that abnormal hematologic findings in patients with schizophrenia should be assessed in the context of a valid reference range. This information will be of value to psychiatrists, laboratory scientists, and other physicians who encounter hematologic problems in patients with schizophrenia, as well as in the assessment of the adverse effects of new therapeutic agents.
*Eli Lilly and Company Limited, Hampshire, United Kingdom; †Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
Received April 12, 2000; accepted after revision August 2, 2000.
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