Uric Acid in the Blood
As to the form in which uric acid circulates in the blood, Sir William Roberts believed that when dissolved in blood serum it was transformed into the relatively soluble sodium quadriurate. This authority held that in gout, either through deficient excretion or over-production, the quadriurate accumulates in the blood. Circulating therein, in a medium rich in sodium carbonate, it takes up an additional atom of the base, and is transmuted into the biurate, which is less soluble and less easily excreted by the kidneys; consequently, the biurate is hoarded up in the blood, at first in gelatinous, and later in an almost crystalline form, when its precipitation is imminent or actually ensues. This, moreover, was apt to occur at sites where the circulation was poor, the temperature low, and more particularly in regions in which the plasma contained a relatively high percentage of sodium chloride, e.g., synovial sheaths.
But, unfortunately for the valency of this otherwise plausible theory, it was proved by Tunnicliffe, Rosenheim, and others, that quadriurates do not exist as definite chemical compounds; in short, it is generally conceded that their existence should no longer be accepted.