Scott MacLeod, the Scotland international lock, faces at least a ten-day fight to clear his name after falling foul of a drugs test for the second time this year - and it could take up to three months before the case is finally resolved.

The player is already in effect on a suspended sentence of a two-year ban arising from the first case, and because he is only 29, if he were to be found guilty, it could end his career.

In the latest drugs test, MacLeod has shown a higher than usual level of testosterone, a hormone that occurs naturally but when taken artificially can help to build muscle mass and help athletes to recover from injuries more quickly than usual. MacLeod is denying any wrongdoing and claims that the level found in the test is not unusual for him.

If he is right, it would certainly not be unique. UK Sport's testing programme has found 35 cases of elevated testosterone in the past three years and only five of them led to guilty verdicts and bans; in every others, the disciplinary panel decided there was no case to answer. There are many natural reasons why a young man's testosterone level could be raised above average, from libido to testicular cancer.

The Scottish Rugby Union (SRU) was told about the finding last Friday and immediately told the Scarlets, the Welsh club MacLeod plays for, that he was suspended from playing until the final verdict in the case. MacLeod was unable to travel with the team to play Stade Français in the Heineken Cup at the weekend, leaving the club without any specialist second rows for the game.

MacLeod has asked for the B sample to be tested, which will delay the verdict in the case, and there will probably be a hearing, which could clear him straight away, find him guilty, or order further tests over the next three months to establish whether his body really does produce extra testosterone. If that were to be the case, then the 21-cap lock, who has played in every Scotland match this year, would be ruled out for the whole of the autumn internationals.

What makes this case tricky for MacLeod is that there are elements of it that echo the case against him in February, when he failed a drug test because of a mix-up in his anti-asthma inhaler. On that occasion he got away with a reprimand and was allowed to keep playing after blaming faulty paperwork. He is again claiming there has been a problem with the administration, this time meaning that a known condition was not covered.

At least the SRU is showing signs of having learnt from its previous experience. Its own rules prevent it from talking about the case until it is over - news of the failed test leaked out from Wales after MacLeod missed the Scarlets' Heineken Cup match - and the SRU restricted itself to a “no comment” yesterday. However, all the indications are that if it does need to put the case before a disciplinary panel, then it is likely to call in the National Anti-Doping Organisation to ensure it is seen to be completely independent - the panel that heard the first case all had strong links with the union.

Because MacLeod is suspended from all rugby, he could not be included in the Scotland training party named yesterday, however there are only three specialist locks in the group, so that if he were to be cleared before the first international, against New Zealand at Murrayfield on November 8, then Frank Hadden, the Scotland coach, could still add him to the group.