TWO titbits of good news emerged in the Scott MacLeod testosterone case last night, a glimmer of optimism in what has been a bleak week both for the player and the Scottish rugby community.

The first shard of light flashed from the offices of UK Sport, where sources denied claims made when the story first broke last week that athletes whose bodies naturally produce higher than normal levels of testosterone must have certification to this effect.

Although MacLeod has yet to officially confirm his intentions, it is expected he will present this reason as explanation for the unusually high levels of the steroid hormone found in his urine sample. Had the 21-cap Scarlets lock been aware of this abnormality and not obtained the requisite documentation, there would have been damaging, and damning, echoes of the case eight months ago where he was reprimanded, but not censured, for failing to arrange an up-to-date Therapeutic Use Exemption (TUE) for the asthma medication, Terbutaline, he employs to treat a condition he has had since childhood.

MacLeod was warned that any future violation would incur a mandatory two-year ban, but if there is no issue of paperwork or procedural negligence in the current case, the 29-year-old must simply be able to show to a judicial panel that a physiological quirk, not steroid abuse, is responsible for the abnormally high testosterone to epitestosterone (T/E) ratio recorded.

The potential make-up of the adjudicatory committee is the other positive signal to be spied yesterday. The composition of the February panel, three Scots with ties to Murrayfield, complied entirely with SRU guidelines but did leave the union open to claims that transparency was not as it could have been. Officials have yet to make a firm decision as to who will sit this time, but it is understood they are moving towards entrusting the National Anti-Doping Panel with the case.

This independent group, launched earlier this year, is presided over by Peter Leaver QC and has a pool of 16 members (nine solicitors or barristers, and seven specialist members with experience in top level sport or doping control). Three officials are appointed to hear any one case. In July, a panel banned mountain biker James Wilson for four months for cannabis use.

Those keen to speculate whether MacLeod is telling the truth should note that of 21 cases involving abnormal levels of testosterone investigated by UK Sport over the past two years, 20 were found to have a physiological explanation.

In accordance with the lengthy analysis procedures favoured by UK Sport in such cases, MacLeod will have been tested a further two times over the three months after the original sampling in January.

Dr Christiane Ayotte, director of the Doping Control Laboratory at Montreal’s Institut National de la Recherche’ Scientifique, said last night that only a tiny percentage of the population naturally produce levels of testosterone that would take them above the 4:1 T/E ratio permitted in sport.

“Only one or two per cent of all samples received for analysis in our lab are given by individuals who normally and systematically excrete specimens with even slightly high T/E values and this is the same elsewhere,” she said. “So a T/E [ratio] at 4, 5 or 6 is an anomaly, but the only way to know whether this is due to doping or normal for the athlete is the IRMS [isotope ratio mass spectrometer] analysis. When done correctly, its results are conclusive.”

The IRMS test measures the relative abundance of two stable isotopes of the same element, in the case of testosterone 12C and 13C, both Carbon isotopes. The test for synthetic testosterone, which has a slightly different atomic make-up to natural testosterone, was developed in the 1990s. If MacLeod’s B-sample also returns an anomalous T/E ratio, it is expected an IRMS test will be carried out to determine whether this is due to naturally occurring or synthetic testosterone.

Floyd Landis, the 2006 Tour de France winner who was later stripped of the title after returning an 11:1 T/E ratio, claimed there were “multiple reasons” for naturally high levels of testosterone, such as high alcohol intake, dehydration and thyroid medication. Dr Ayotte contradicts this view, saying “the only way to physiologically elevate the T/E [ratio] is the ingestion of a very high, inebriating dose of alcohol - to be dead drunk. Even in that case, the IRMS would indicate a normal/body origin, not doping.”

MacLeod’s B-sample result is expected to be known, privately at least, within the next two weeks. If he were then found guilty of steroid abuse, he would be banned from the sport for two years.