Random distribution of exogenous lithium in nasal secretion and its application in substance determination.

The use of lithium as an exogenous marker to determine the dilution of nasal spray washing samples was investigated in vitro and in vivo. The correlation coefficient between the true and calculated dilution determined in vitro, using pooled secretions, was 0.99 (p less than 0.001). Thirteen washings from healthy subjects contained 5-22% secretion, while five washings from asymptomatic allergic patients contained 21-39%. The described application of exogenous lithium as a marker of dilution of nasal secretion seems a promising tool for use when a washing method is employed to take samples for biochemical investigations.