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Dialysis of saliva improves accuracy of saliva lithium determinations


Rif S El-Mallakh, Mood Disorders Research Program, Department of Psychiatry, University of Louisville, Louisville, KY 40292, USA. Fax: (502) 852 1115;


Background:  Saliva lithium (Li) determinations have been explored as a potential alternative to plasma levels. Unfortunately, this method has been shown to be unreliable. Saliva has two major components: the aqueous and the mucopolysaccharide portions.

Methods:  Since Li is likely to distribute only in the aqueous fraction, we dialyzed the saliva through a 3000 Da filter to isolate the aqueous component and determine the Li level in it.

Results:  Lithium levels in the dialyzed saliva agreed more closely with plasma levels (Spearman's rho = 0.901, p < 0.001) than did whole saliva (Spearman's rho = 0.775, p = 0.012).

Conclusion:  Dialysis of saliva may contribute to more accurate saliva Li levels.