STEVE INSKEEP, host:
A British hospital says the condition of a former Russian spy has deteriorated. Doctors are trying to figure out what poisoned him.
NPR's science correspondent Richard Harris takes us through the clues.
RICHARD HARRIS: When former KGB spy Alexander Litvinenko showed up miserably sick at the hospital there was no magic blood test the doctors could use to figure out what had poisoned him. So says Suzanne Doyon, medical director at the Maryland Poison Center.
Dr. SUZANNE DOYON (Medical Director, Maryland Poison Center): You basically have to have some clinical indication, something directing you as to what to test for.
HARRIS: One indication was Litvinenko lost his hair a few weeks after the suspected poisoning incident. That's a symptom of poisoning by the heavy metal thallium; it's a rat killer also known to be used in the world of spooks. But Dr. Doyon says hair loss has lots of possible causes.
Dr. DOYON: That has been known to occur after radiation injury. It has been known to occur after a heavy metal exposure. It also has been known to occur if you're exposed to very high doses of agents used for the management or the treatment of cancer.
HARRIS: And Litvinenko's bone marrow had also reportedly failed.
Dr. DOYON: We don't see that usually with thallium poisoning. So it suggested that something else is the major actor or a combination, which is always a possibility.
HARRIS: If it is a combination of poisons, that makes it even harder to figure out, Dr. Doyon says. And doctors always want to know what caused poisoning as soon as possible because there are many antidotes and treatments if you know what you're dealing with. But in this case, doctors may never figure out exactly what Litvinenko ingested.
Richard Harris, NPR News.
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