Circulating plasma testosterone in the XYY male

A population of 6 XYY and 6 XY individuals participated in a study to compare the levels of free circulating testosterone. No significant differences were found in the amounts of free circulating testosterone or total plasma testosterone. The plasma testosterone levels of the twelve subjects were within the normal range of values (596ng/dl ± 232ng/dl) obtained in our laboratory. Estrogen levels were assayed to determine estrogen influence on testosterone levels. Estrogens were not significantly different in the two groups. Plasma estrogens were within the limits of a random normal population (15–55pg/nl).