The amino acid factor in stone formers' and normal urines.

The composition of amino-acids in kidney stone matrices and inhibitory materials from normal urines, reported in different independent studies has been reviewed. No obvious difference was found between the composition of amino acids from healthy and pathological sources. Studies carried out in this laboratory showed a specific marked effect of glutamic acid on the crystallization of calcium oxalate while aspartic acid and alanine affected the process very slightly. It is known that aspartic acid and alanine are transformed into glutamic acid by enzyme activity. A short survey performed in this laboratory showed that the relevant enzyme activity was relatively high in healthy urine and low in stone formers' urine. The AA factor (FAA) proposed is FAA = [Glutamic acid]/[( Aspartic acid] + [Alanine]) its value in fractions of non-potent inhibitory material and in kidney stone matrices is below 0.6. In potent portions of the inhibitory material separated from healthy people and young animals urine the value is 0.8 and above.