Measurement of Cortisol in Small Quantities of Saliva

The determination of cortisol in saliva has become popular for human research on stress reactions (1)(2)(3)(4)(5). Depending on the sensitivity and reliability of the assays used, the required sample volume varies between 0.025 and 2 mL of saliva (6)(7)(8). Infants and toddlers, however, often produce only small amounts of saliva and are usually sampled by swabbing the mouth with cotton dental rolls (5) or commercial cotton swabs (Salivette; Sarstedt Inc.) (9), or by pipettes or alternative devices that aspirate saliva from the floor of the mouth (10)(11)(12)(13). Cotton rolls must either be centrifuged to obtain saliva (9) or be placed in the barrel of a syringe (needleless), from which the saliva is expressed into a vial by compression of the plunger (5). With these procedures, saliva remaining in the swabs is thus lost for analysis. When we tested seven different types of cotton rolls, we found that, depending on the individual type, 135–450 μL of saliva could not be centrifuged from the rolls.