title: On the Merits of Tetrapolar Impedance Spectroscopy for Monitoring Lithium Concentration Variations in Human Blood Plasma.
abstract: Bipolar disorder is characterized as a manic-depressive psychiatric syndrome with life-threatening risks to the patient. Diagnosed individuals undergo long-term lithium therapy which has proven to be effective for mood stabilization. Maintaining blood lithium concentration levels within a narrow therapeutic window between 0.6 and 1.5 mM is vital for the patient as slightly elevated concentrations of the order of 0.1 mM can be toxic. This paper aims to evaluate the merits of tetrapolar electrical impedance spectroscopy as an alternative method in monitoring blood lithium levels. Measurements were performed using a custom-made tetrapolar probe in human blood plasma with lithium concentrations covering the therapeutic range. The results indicate a limit of detection less than 0.1 mM and a response time of less than 5 s. Prediction of lithium concentration levels using impedance values is in good agreement with conventional standard techniques to approximately 0.05 mM. This technique provides a basis for further development of instrumentation for point of care healthcare technologies.
authors.forename: Loukas
authors.initials: L
authors.lastname: Constantinou
authors.forename: Iasonas F
authors.initials: IF
authors.lastname: Triantis
authors.forename: Michelle
authors.initials: M
authors.lastname: Hickey
authors.forename: Panayiotis A
authors.initials: PA
authors.lastname: Kyriacou
mesh_terms: D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000379:methods; D017076:Computer-Aided Design; D058266:Dielectric Spectroscopy / Q000295:instrumentation* / Q000379:methods; D016903:Drug Monitoring / Q000295:instrumentation* / Q000379:methods; D004553:Electric Conductivity; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D018020:Lithium Compounds / Q000097:blood* / Q000627:therapeutic use; D008832:Microchemistry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D018020:Lithium Compounds