Hormones have not been found in concentrations of orders of magnitude higher than nanograms per milliliter. This study reports urine concentrations of a catecholamine (norepinephrine) ranging from 0.05 to 0.5 g/l, and concentrations of its metabolite dl-3,4-dihydroxyphenyl glycol (DOPEG) ranging from 1.0 to 44.5 g/l, in wild male red deer Cervus elaphus hispanicus after LC–MS analyses. The dark ventral patch of male red deer, a recently described sexually selected signal, contains high...