RESUMEN
Objective To establish a candidate reference method for the determination of serum lithium based on ion chromatog-raphy and evaluate its analytical performance.Methods A simple sample treatment procedure,which can be remove the proteins and/or organics in human serum,has been developed for the determination of serum lithium.Method precision was evaluated with different concentration of fresh human serum and EQA sample RELA-A/B.Method accuracy was investigated with the recovery ex-periments in fresh human serum and RELA-A/B sample.Results The linear equation was Y =0.817 1X -0.001 3 with a correla-tion coefficient of 0.999 95 under the optimum experimental conditions,the detection limit (3S/N)for lithium was 6 μg/L and the imprecision was less than 1.0%.The results of the recovery experiments indicated that the recoveries were reasonable for the deter-mination of serum lithium,in a range of 99%-101%.Conclusion The candidate reference method of lithium was successfully es-tablished and which can be used for traceability and standardization.It may provide an effective way for routine testing of lithium traceable to the reference method/reference material.
RESUMEN
OBJECTIVES: It was reported that symptoms change according to menstrual cycles, aggravation of symptoms 3 to 7 days before menstruation in bipolar disorder for example. Therefore, this study was to investigate the correlation among the change of symptoms, serum lithium level, estradiol and progesterone levels. METHODS: For women with bipolar disorder, we divided by menstrual cycle into three groups; middle follicular phase, middle luteal phase and late luteal phase. We estimated serum lithiumlevel, estradiol and progesterone of each phase, and assessed the change of symptoms using Hamilton Rating Scale for Depression and Manic-State Rating Scale. Consequently they were divided into symptom changed group and not changed group. RESULTS: Serum lithium levels of patients with bipolar disorder were significantly decreased in middle luteal phase compared with in middle follicular phase, and it was sustained in low level to late follicular phase. Although there were no statistically significant differences, there was more decreased serum lithium level in symptom changed group than in symptom unchanged group. Serum lithium levels were not statistically correlated with both estradiol and progesterone levels. When symptom changed group was compared with symptom not changed group, there was a significant correlation between changes of symptom and estradiol level. CONCLUSION: The possible mechanism of the change of symptoms according to menstrual cycle in bipolar disorder may be in estrogen level and due to the effect of serum lithium level change according to menstrual cycle. The investigation of this mechanism will contribute to the treatment and the prevention of recurrence symptons in bipolar disorder.