The Dutch sports body NOC*NSF is taking steps to prevent athletes abusing medicine for treating thyroid problems by making a second opinion from an endocrinologist compulsory, the Volkskrant said on Thursday.

The organisation says sports doctors should not be able to prescribe medicine for treating a slow thyroid without the input of an expert.

‘I am putting an extra lock on the door,’ NOC*NSF medical director Cees-Rein van den Hoogenband told the paper. ‘I don’t want this hassle any longer… and yes, [the decision] will raise questions.’

Last July the Dutch skating union KNSB wrote to all the country’s top skaters about the possible abuse of thyroid medication and the Dutch doping authority is also concerned about its use, the paper said.

The drugs are used to treat people who have a slow thyroid but in some circles are thought to boost performance and help weight loss.

The measures will be discussed with sports doctors in April, the paper said.

Thyroid medication is not currently on the sports banned list although the US and British doping authorities have requested that it be included, as well as the Dutch skating union.