The American Thyroid Association guidelines on thyroid nodules and differentiated thyroid cancer, published in 2009, provide valuable recommendations based on current evidence. Inevitably, controversies and uncertainties will continue to challenge clinicians and patients. On topics where evidence is not clear-cut, judgement may be coloured by pre-existing practises and the structure of the health service in each country, so one has to be aware of the pitfalls of transferring recommendations to one's own practise.