Doctors treating the former KGB agent Alexander Litvinenko said last night that he is unlikely to have been poisoned with the toxin thallium and the cause of his symptoms was unknown.
Early tests had indicated that Mr Litvinenko, 43, a strident critic of the Russian President, Vladimir Putin, was poisoned on 1 November with a thallium salt, which is tasteless, odourless and deadly in very small quantities. But Dr Amit Nathwani, the consultant caring for Mr Litvinenko at University College Hospital in central London, said: "We have requested toxicology tests to establish what poisoned him. Based on results we have received today and Mr Litvinenko's clinical features, thallium poisoning is an unlikely cause of his current condition. Further tests will be carried out to establish whether or not there is a single cause for Mr Litvinenko's condition."
In a further twist, a hospital source said last night that three pieces of "dense matter" had been found in Mr Litvinenko's colon or small bowel.
Medical staff have not been able to ascertain what they are, but an additional x-ray ordered yesterday afternoon revealed one was the size of a 2 pence piece, the other was shaped like a figure 8, and the third larger still. Given that they had reached Mr Litvinenko's colon, they would have already been ingested.
Dr Nathwani added that a precise cause of the poisoning might never be known, and his treatment could last months.
Doubts about the presence of thallium were raised after Mr Litvinenko, 43, suffered a collapse of his bone marrow function and infection-fighting white cells, symptoms that are not associated with the poison.
Professor John Henry, a leading toxicologist, said: "Mr Litvinenko has signs and symptoms which are unexpected and do not normally occur with thallium poisoning, especially the fact that his bone marrow is not functioning and his white cell count has dropped to zero." The academic, based at St Mary's Hospital in west London, who is advising on Mr Litvinenko's treatment, said he believed a radioactive substance, including a radioactive version of thallium, had been swallowed by him.
But it was unclear whether Mr Litvinenko could have swallowed enough of the radioactive thallium 201 to suffer such extreme symptoms. Low doses of thallium 201 are used as a "tracer" in hi-tech scans for heart disease. Dr Nathwani said it was "speculation" that a radioactive substance was the cause of Mr Litvinenko's condition.
His medical team were investigating whether he was given a drug similar to those used in cancer chemotherapy, which would be capable of killing off bone marrow. Professor David Coggon, a specialist in environmental medicine at Southampton University, said: "Radiation doses have to be relatively high to cause short-term toxic effects."
Friends of Mr Litvinenko, a former pentathlete who ran five miles every day, said his condition had further deteriorated. Doctors have said he has a 50-50 chance of surviving the next three or four weeks.
Alex Goldfarb, who helped the Russian officer seek asylum in Britain after he turned whistleblower on the KGB's successor, the FSB, said: "We have to wait to see if his immune system responds. The last resort is for him to have a bone marrow transplant."
The former lieutenant-colonel in the FSB's organised crime unit fell ill after two meetings in London, one with an Italian academic and examining magistrate, Mario Scaramella, at a sushi bar in Piccadilly, the other with two Russians, one of whom was the former KGB agent Andrei Lugovoy.
Mr Litvinenko believes he was poisoned because he made allegations of criminal activity against his former employer. The Kremlin denies any involvement.Reuse content