Swiss triathlete Brigitte McMahon, who admitted on Friday taking a banned performance-enhancing hormone, has announced her retirement.
She won Switzerland’s only gold medal at the 2000 Olympic Games in Sydney.
The Swiss Olympic Association said the drug test was conducted at McMahon’s home last month and the banned substance erythropoietin (EPO) was detected in her blood.
She now faces a two-year ban and has been deselected from the national squad with immediate effect.
On Sunday McMahon announced her retirement from competitive sport.
She had earlier admitted to having taken EPO "for therapeutic purposes and in small doses".
She said that after returning from a spring training camp she suddenly felt weak and listless and her blood levels had gone through the floor "in many areas including the number of red blood cells".
EPO, which increases the number of red blood cells in the blood, has been extensively used as a doping drug in some sports – particularly cycling and long-distance running – because higher amounts of red blood cells can increase the oxygen-carrying capacity of the blood and improve endurance.
The Swiss Female Athlete of the Year 2000 did not want to name her supplier, saying "ultimately it is my responsibility".
Within the last two years the mother of three has had to cope with the death of her father - who fell out of a tree house while playing with her children - and her divorce from Michael McMahon, who was also her trainer in Sydney.
But she insisted that her Olympic gold medal was achieved without illegal substances. "Before this spring I had never been offered any doping drugs," she said.
McMahon came 10th in the women’s triathlon at the Athens Olympics in 2004. The 38-year-old athlete was training for next year’s world championships and said she was hoping to qualify for the 2008 Games in Beijing.
McMahon is the second prominent triathlete to admit to taking performance-enhancing hormones.
Last October, Germany’s Nina Kraft tested positive and admitted to taking EPO.
swissinfo with agencies
Brigitte McMahon has admitted using the performance-enhancing drug, EPO, and now faces a two-year ban.
She won the triathlon competition at the 2000 Sydney Olympics in triathlon.
She came 10th in the women’s triathlon at the Athens Games last year.