You wouldn't ask a vet to treat a human, would you?' a doctor asks. But animal medicine is all the experts had to go on when infants began turning up at hospitals on the mainland with kidney stones caused by dairy products adulterated with melamine. The problem had only been seen once before on such a large scale - last year when dogs in North America were found to have excessive amounts of melamine from eating pet food manufactured on the mainland. Most of the animals died within days. 'The few papers that have been published [on melamine-induced kidney stones] mostly deal with animal models, like rats,' said Caleb Nelson, a urology specialist at Harvard Medical School. 'Kidney stones are very difficult problems to treat in babies ... and can lead to major complications. For this reason the melamine crisis in China is a public-health catastrophe, the scale of which is hard for us here to imagine.' Kidney stones in babies are extremely rare, though not unheard of. They usually affect two babies per one million. But no one had envisaged devising a treatment programme for more than 53,000 victims, made ill by a chemical normally used to make glue and plastic. China's Health Ministry said this week that 5,800 children were still being treated in hospitals, including six who were in serious condition. As it did with Sars, Beijing has asked for advice from overseas. Two weeks ago, mainland authorities began talks with the US Department of Health medical research agency, the National Institute of Health, according to a source. The US Food and Drug Administration (FDA) is experimenting with several treatments, including one developed by a Hong Kong doctor. Meanwhile, Hong Kong's Food and Health Bureau is expected to recommend a treatment in its next newsletter. So what is the consensus? A comment by Dr Nelson sums it up: 'I don't think anyone knows for certain what the best way to treat melamine stones is.' Kidney stones can take months to become life-threatening. In infants they block urination, which eventually leads to bacterial infection in the urinary tract. Mark Chan Kwok-ho, a consultant paediatrician at Matilda Hospital, identified another problem. As do a growing number of doctors overseas, Dr Chan suspects that the current treatment protocol hardens rather than dissolves the stones. The consequence of using the wrong treatment could take months to become apparent, he says. But Tse Hung-hing, chairman of the Hong Kong Medical Association, scoffs at the suggestion. 'Do these doctors have experience treating these patients?' he said. 'No. As far as I know, the standard protocol is alkalisation, and it seems to work. We don't listen to speculators in the medical industry, just like you wouldn't in the financial industry.' Along with several colleagues, Dr Tse returned from visiting Guangzhou hospitals last week, and expressed confidence in the treatment. 'I think Chinese hospitals are well equipped,' he said. 'We don't need any sophisticated techniques or pioneer work to detect the stones, screening only requires a urine test, blood test and ultrasound. This is common equipment that can be found, even in China.' But Dr Chan says this attitude dangerously narrow-minded. 'I think for some doctors, the idea of going from animal toxicology to animal medicine to human medicine is ridiculous ... I'm not saying I'm right, I just want people to consider there could be a better option.' Dr Chan says that in Hong Kong his theory is usually met with ambivalence or a lack of interest. 'I think China knows how to handle treating its own babies,' was the response he received from one paediatrician. He suspects that many doctors in Hong Kong 'are afraid of appearing like they are telling mainland doctors what to do'. At the heart of the treatment debate is whether an alkaline or acid substance should be used to dissolve melamine-induced kidney stones. The widespread recommendation on the mainland is to dissolve them with alkalinity, which some hospitals in Guangzhou have been inducing through tiny sips of soda water. But Dr Chan says acidification should be used because of the presence of another chemical in the stones, cyanuric acid, previously identified in North American pets' kidney stones. Cyanurate, he says, should be dissolved by an acid treatment such as ammonia. 'It would be terrible if, months down the line, we found the treatment being given was making the babies worse,' he said. Dr Chan is awaiting the result of an FDA experiment based on the acidification theory, but anticipates any response could 'take a while'. Michael Somers, chairman of the clinical affairs committee of the American Society of Paediatric Nephrology, agrees that acid is better for dissolving cyanuric acid. However, he understands why mainland doctors favour the alkaline option. 'Clinically, it is much easier to alkalinise urine than to acidify it ... I suspect that ease, safety, and familiarity underlie why alkalisation is being done,' Dr Somers said. '[But] from conversations with other doctors here there is a good amount of energy going into this whole issue of acidification and attempts to construct ways to do this readily and safely.'