You have been treating Mr. Peppard, aged 70, for a number of years. He has had gout and returns every 6 months for review and repeat of his medication. He is taking allopurinol 100 mg daily and he has been free of attacks and side effects since he started taking it. His serum uric acid is normal. Today he tells you he has noticed increasing shortness of breath for the last few months. He "suspects it is due to old age". Mr. Peppard has no other symptoms.