If we may believe Altman and De Roos, the true cause of Beethoven's death was not the bad liver, but... poison, deliberately given by people who wanted to get rid of the dissident composer. This assumption is highly hypothetical and speculative, since there is not the slightest trace of a proof that somebody wanted to murder Beethoven. Nevertheless a considerable amount of lead has been found in his hear and his bones, at least according to the chemists who analyzed both hair and bones, by order of the Ira F.Brillant Center for Beethoven Research. Experts (Reiter, Eisinger) strongly disagree on the quality of this reseach. However, assuming that the amount of in Beethoven's was extraordinary high, we still can safely assume that this lead had entered his body by natural causes, like food, drink and/or medicines. It is also not very likely that he died of lead poisoning or, even more unlikely, that lead caused his deafness. Beethoven did not show the usual symptoms of lead poisoning.
See:
De Roos, Harke. Beetgenomen door Beethoven. (Katwijk aan Zee, the Netherlands, 1987).
Altman, Gail. Fatal Links. The curious deaths of Beethoven and the two Napoleons. (Tallahassee, 1999).
Walsh, William J. Press release of October 17 of The Health Institute and Pfeiffer Treatment Center on the chemical study of Beethoven's hair. (Naperville, USA, 2000).
Weiss, Rick. Study Concludes Beethoven Died of Lead Poisoning. In: The Washington Post. (December, 6, 2005).
Reiter, Christian. Beethovens Todesursachen und seine Locken. In: Mitteilungsblatt der Wiener Beethoven-Gesellschaft. (2007).
Eisinger, Joseph. Was Beethoven Lead-Poisoned? In: The Beethoven Journal. (San Jose, 2008).