Direct assay for testosterone in saliva: relationship with a direct serum free testosterone assay

A direct non-extraction radioimmunoassay for salivary testosterone is described using a modified commercial kit procedure that is in use for total serum testosterone (T). Serum free testosterone was also measured by direct radioimmunoassay. A significant correlation (r = 0.83, p less than 0.01, n = 194) was obtained between salivary and serum free testosterone in matched serum and saliva samples over a wide range of concentrations. Within- and between-batch precision for the salivary testosterone method was 11% and 18%, respectively at a concentration of 170 pmol/l. Recovery of added T was 89% +/- 15% (mean +/- 2 SD) dilution of high samples showed parallelism. Salivary testosterone measured by direct radioimmunoassay offers a simple cheaper alternative to serum free testosterone measurement with the additional advantages of a stress-free non-invasive sampling procedure.