Objective: It is estimated that, there are about 17 million opioid addicts worldwide. However, it is observed that there are limited number of studies about whether opioids have any effects on hematological parameters. The aim of this study was to investigate the effects of opioid addiction on the leukocyte count, erythrocyte count, platelet count, hemoglobin, hematocrit levels, and platelet indices.

Materials and Methods: Fifty male patients with opioid dependence and thirty-five healthy male controls were included in the study. All of the urine samples were analyzed for opioid metabolites by cloned enzyme donor immunoassay technique. Hematological parameters were tested by electrical impedance method.

Results: The leukocyte and erythrocyte countes of opioid addicts were similar with control group (P= 0.10, P= 0.45 respectively). Although platelet count was higher in the opioid addicts, this difference was not statistically significant (P= 0.08). Whereas the mean platelet volume and plateletcrit values of opioid addicts were significant higher than healthy control group (P<0.001, P<0.001 respectively), their platelet distribution width, hemoglobin and hematocrit values were significantly lower (P<0.001, P= 0.001 and P<0.001, respectively).

Conclusion: It was observed that opioid dependence may lead to anemia by lowering hemoglobin-hematocrit levels.However, it was shown that opioid dependence may affect the platelet functions with its effects on the mean platelet volume, platelet distribution width and plateletcrit values. New deterrent and preventive measures should be taken to avoid opioid dependence, which places additional financial burden on health spending of countries in many ways.