Objectives:
Few scientific reports indicate changes in the concentration of magnesium in the blood of patients with bipolar disorder (BD). So far very little studies concerning these issues have been conducted. Therefore, the aim of this study was to evaluate the serum magnesium level in patients with bipolar disorder (in different phases of the disease) in comparison to healthy volunteers.

Methods:
The study included 129 patients (58 subjects in depressive episode, 23 in manic episode and 48 patients in remission) with the diagnosis of bipolar disorder type I or II. The control group consisted of 50 healthy people. Magnesium concentration was measured using flame atomic absorption spectrometry (FAAS).

Results:
Patients with a current depressive or manic/hypomanic episode had statistically significantly elevated serum magnesium levels compared to healthy volunteers. Moreover, a positive correlation between the duration of the manic/hypomanic episode and the relapse frequency in the last year was observed. The concentration of magnesium in patients in remission was unchanged in relation to the control group.

Conclusions:
Presented findings suggest a role of serum magnesium level as a potential state marker, reflecting the pathophysiological changes associated with acute episodes of bipolar disorder.