Methodology for rapid assessment of blood lithium levels in ultramicro volumes of blood plasma for applications in personal monitoring of patients with bipolar mood disorder

Bipolar disorder (BD) is a common mental health condition, characterized by extreme changes in mood, energy, and behavior. BD is often managed through mood-stabilizing medications, of which lithium formulations remain the most reliable and effective at reducing the risk of suicide. To achieve adequate and consistent efficacy, lithium concentrations need to be maintained within a narrow therapeutic range (0.4 to 1.2  mmol  /  L). Because of its narrow therapeutic index, long-term lithium therapy is associated with serious side effects and risks of toxicity. It is believed that the availability of a personal blood lithium analyzer would benefit patients who are on lithium treatment. We detail the results of a spectrophotometric method performed on ultramicro volumes to determine blood plasma lithium concentrations as compared with reference measurements of flame photometry, and validated in samples of unknown lithium content. Applying multiple linear regression, lithium concentrations could be determined in a rapid manner using full-range spectra or triwavelength data. Both techniques highly correlated with reference standards and could predict lithium levels accurately (R2  =  0.794214 and RMSEP  =  0.209584, and R2  =  0.863921 and RMSEP  =  0.167524, respectively). Therefore, this method can be a useful for rapid assessment of blood lithium in nonlaboratory settings i.e., general practices, hospital clinics, and community health centers by healthcare professionals and/or by patients. Future work will now focus on completion of a miniaturized and integrated system that will deliver a portable and personal lithium-monitoring device.