Problems associated with the analysis and interpretation of saliva lithium

Area of Science:

• Pharmacology
• Clinical Chemistry

Background:

• Lithium prophylaxis therapy requires regular monitoring of lithium levels.
• Serum lithium measurement is the standard, but saliva analysis is explored as a less invasive alternative.

Purpose of the Study:

• To evaluate the reliability of saliva lithium levels as a predictor of serum lithium levels in patients undergoing prophylaxis therapy.
• To investigate strategies for improving the accuracy of saliva lithium monitoring.

Main Methods:

• Assessed the correlation between paired serum and saliva lithium measurements.
• Employed two strategies to enhance reliability: using a naturally occurring marker and analyzing serially paired results in individual patients.

Main Results:

• A high overall correlation between serum and saliva lithium levels was observed.
• However, significant and unacceptable individual variations in paired results were consistently found.
• Neither the use of a natural marker nor serial sampling prevented occasional excessive variations.

Conclusions:

• While a correlation exists, saliva lithium monitoring is currently considered an unreliable technique for predicting serum levels.
• Further research is needed to develop dependable methods for saliva-based lithium monitoring.