Analytic Evaluation and Application of a Novel Spectrophotometric Serum Lithium Method to a Rapid Response Laboratory

Abstract

The authors present an evaluation of the Lithium DST spectrophotometric method developed by Thermotrace (Victoria, Australia) on a Hitachi 917 analyzer. Accuracy was assessed by method comparison with an ion-selective electrode (ISE; Roche Integra 700) (n = 80). Linearity, within-run and between-run precision, and susceptibility to interference by hemolysis, icterus, lipemia, and sodium were assessed. The method was linear to 3.0 mM/L, and analyzer auto-dilution extended the reportable range to 7.2 mmol/L. Within-run coefficient of variation was 1.5% at 0.68 mmol/L and 0.7% at 2.06 mM/L. Between-run precision for the same lithium concentrations assayed daily for 20 days were 3.1% and 1.9%, respectively. Method agreement with ISE was excellent, with an intercept of 0.000 and slope of 1.000 by Passing Bablock regression analysis. Hemolysis, icterus, lipemia, and high and low sodium levels did not significantly interfere. The manufacturer's recommended calibration stability of 1 week was confirmed. The authors conclude that this method is reliable, accurate, and precise. The Thermotrace serum lithium spectrophotometric method provides a useful alternative to ISE or flame photometry, facilitates workstation consolidation on the Hitachi 917 multiple-channel analyzer, and is well adapted for use in a rapid response laboratory.

A highly Li+-selective glass optode based on fluorescence ratiometry

“…Hence, there is a demand to monitor the Li + concentration in blood effectively and safely. 3,4 However, it is a challenging task to develop simple and robust methods for the selective determination of Li + concentrations among coexisting alkali and alkaline earth metal cations as well as many biological materials in blood.…”

Existing and Emerging Technologies for Therapeutic Monitoring of Lithium

“…All studies had detection limits below therapeutic lithium levels, which is essential. However, one study (28) that used capillary electrophoresis and microchips had a lower detection limit of 0.4 mmol/L, which is within the lower therapeutic range of lithium and can generate mistrust for decision making.…”

“…Table 1 shows the 14 studies with strictly laboratory technologies. Of these, 50% (n = 7) had good precision (RSD < 3%), 17,19,21,25,28,29,31 14% (n = 2) an acceptable precision (RSD between 3% and 5%), 17,28 and 36% (n = 5) had low precision with an RSD >5%. 19,20,23,27,32 The accuracy of 5 studies (36%) was good, [16][17][18]21,22 another 4 (29%) had low accuracy, 20,22,26,27 and 5 other studies did not report accuracy.…”

“…19,20,23,27,32 The accuracy of 5 studies (36%) was good, [16][17][18]21,22 another 4 (29%) had low accuracy, 20,22,26,27 and 5 other studies did not report accuracy. 16,19,24,25,28 Table 2 reflects the 8 studies that developed portable devices. Regarding precision, 63% (n = 5) of the portable devices had low precision 27,[32][33][34][35][36] ; for 12% (n = 1), it was acceptable, 30 and only 25% (n = 2) had good precision, 15,31 without being able to establish a relationship with any particular technique.…”