Platelet volume variation in major psychiatric disorders

Objective: Mean platelet volume (MPV) is one of the indicators of platelet function. Changes in platelet function have been reported in many psychiatric disorders. Increased intra-platelet calcium mobilization, upregulation of 5-HT2 receptors or α2-adrenoreceptors, down-regulation of 5-HT transporter number, changes in second messenger signal transduction and intra-platelet concentrations of monoamines or catecholamines are some potential underlying factors. Psychotropic medications could also be one of the main factors of altered platelet volumes. It was aimed to compare MPVs of different psychiatric disorders in order to find out whether this effect is due to medications in this study. Since treatment regimes of these disorders vary, differences between groups may show the effects of medications on MPV.

Methods: Records of the first hemogram tests (CBC) of the patients (n=954) admitted to the psychiatry outpatient unit of the psychiatry department of Ankara Ataturk Training and Research Hospital were obtained. According to ICD-10, patients with depressive disorders (n=389), bipolar disorders (n=338) and psychotic disorders (n=227) were included in the study. Mean platelet volume (MPV), platelet distribution width (PDW), platelet count (PLT), leukocyte count (WBC) and erythrocyte count (RBC) were obtained from laboratory records. Groups were compared with One-way ANOVA test. Tamhane and Bonferroni tests were the post-hoc tests.

Results: Statistically significant differences were found between age (F(2,953)=11.31, p=0.000014), gender (p=0.000103, χ2=23.44), platelet count F(2,953)=3.45, p=0.032, leukocyte count F(2,953)=461,01, p<0.0000001 and erythrocyte count F(2,953)=351.11, p<0.0000001. There were no significant differences between MPV F (2.953)=2.29, p=0.102 and PDW F(2,953)=1.29, p=0.277. Platelet count was significantly higher in the bipolar disorders group (260.03+66.66 K/μL) than the depressive disorders group (247.30+67.30 K/L). Leukocyte count of the depressive disorders group (7.88+2.28 K/μL) was significantly higher than bipolar disorders (4.83+0.56 K/μL) and psychotic disorders (4.93+0.46 K/μL) groups (p<0.0000001 for both comparisons). The depressive disorders group (4.83+0.46 M/μL) had significantly lower erythrocyte count than the bipolar disorders (7.39+2.03 M/μL) and the psychotic disorders group (8.03+2.19 M/ μL) (p<0.0000001 for both comparisons).

Conclusion: Although MPVs were in the reference interval (7.7-11 K/μL), values of all groups were close to the upper limit of reference range. Furthermore, platelet count in bipolar disorders group was significantly higher than in the depressive disorders group, which suggests that mood stabilizers stimulate production of platelets. Investigating the effects of drugs on the process of thrombopoiesis could be promising to provide biomarkers to monitor medication effects via peripheral blood sample. We found that the leukocyte count was higher in psychotic disorders group and bipolar disorder group. Neuroendocrine and inflammatory processes may be related with the findings.