Caster Semenya completed the first half of an intended Commonwealth Games golden athletics double on Tuesday night, but her career could be coming to a shuddering halt later this year.

The South African track star — a two-time Olympic gold medallist in the 800m — has hyperandrogenism, meaning she has an excess of male sex hormones in her body, including testosterone.

It has seen her battle controversy throughout her career, having undergone sex verification tests back in 2009 following the world athletics championships which saw her make huge time improvements to her 800m and 1500m events.

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On Tuesday she took out the 1500m event comfortably, in Commonwealth record time, and she is due to run in the 800m heats on Thursday. The final in her specialty event is on Friday as she chases a second gold in her first-ever Commonwealth Games appearance.

But that could be where the career highlight reel ends, if the IAAF has its way.

Athletics' global governing body hopes to bring in regulations that will limit testosterone levels in female athletes by November this year, meaning Semenya will either have to take medication that will bring her body's levels down, or quit the sport.

The Court of Arbitration of Sport (CAS) had given the IAAF a deadline to provide scientific evidence for its suspended 2011 rules over hyperandrogenism, as well as advice on how the governing body intends to implement the proposed regulations.

Regulations appear to target Semenya's disciplines

The regulations are based on a 2017 IAAF-commissioned study which looked into competitive advantages in certain disciplines for female athletes with higher levels of testosterone.

In its summarised conclusion, the study found athletes with the higher concentrations performed better in the 400m, 400m hurdles, 800m, hammer throw and pole vault "with margins of 2.73 per cent, 2.78 per cent, 1.78 per cent, 4.53 per cent, and 2.94 percent respectively".

But interestingly, the IAAF's policy omits hammer throw and pole vault — which the study showed had the highest margins of improved performance — and throws in the 1500m for good measure. So that's a policy which covers a range of 400m through to 1500m races, all in Semenya's zone of specialty.

In an IAAF press release published in July 2017, one of the study's authors said their starting position was to "defend, protect and promote fair female competition".

"If, as the study shows, in certain events female athletes with higher testosterone levels can have a competitive advantage of between 1.8 to 4.5 per cent over female athletes with lower testosterone levels, imagine the magnitude of the advantage for female athletes with testosterone levels in the normal male range," author Dr Stephane Bermon said. "This study is one part of the evidence the IAAF will be submitting to CAS regarding the degree of performance advantage that hyperandrogenic female athletes enjoy over female athletes with normal testosterone levels. We continue to gather more data and research on our journey to providing a fair and level playing field for females in our sport."

Australia's McGowan says comparisons with Semenya unfair

Semenya has had to deal with short shrift from competing athletes for much of her career, and that has continued in her maiden Commonwealth Games meet.

Australia's Brittany McGowan, who will run in the 800m heat after Semenya, kicked off the issue earlier in the Games, saying it was unfair to compare her times and other athletes' performances with the times posted by the South African.

"It's a tough one. It's tough for a lot of women in the 800m, 400m and 1500m at the moment to compare ourselves and be judged by our governing bodies on those times," she said.

IAAF president Sebastian Coe said it was one of the toughest subjects global athletics has to address.

"I want to make one point crystal clear, this is not about cheating, no athletes have cheated," Coe said.

"This is about our responsibility as a sports international federation to ensure, in simple terms, a level playing field.

"It is our sport and it is up to us to decide the rules and the regulations.

"We draw the lines at two classifications for our competitions, men's events and women's events. This means we need to be clear about competition criteria for those two categories."

Semenya's first Games win likely the first half of golden double

Semenya looks set for a golden double at the Commonwealth Games after her win in the women's 1500m. ( AAP: Tracey Nearmy )

Amid the controversy and endless discussion surrounding her, Semenya still clutches one Commonwealth Gold after victory in the 1500m.

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Semenya's win in 4:00.71 broke the Commonwealth record and was nearly three seconds in front of Kenya's silver medallist Beatrice Chepkoech.

"I am very happy with how I performed tonight. I'm proud of my efforts," Semenya said.

"It is difficult and I have prepared [for the 800m and 1500m] with more endurance. It is quite difficult, but I have to lead by example.

"If I say I am going to do something you have to try and do it. Hopefully this will help motivate other athletes in South Africa.

"I want everyone to know that South African athletes are here to stay. I'm proud to be a South African.

"We are a great nation and we want to display that to the world."

She is likely to race in the women's 800m on Friday, where she would be overwhelming favourite to clinch a second gold on the Gold Coast.