STUDIES ON FREE AMINO ACID EXCRETION PATTERNS IN THE UPPER URINARY CALCULOSIS

THE 1ST. REPORT: SEX AND AGE-RELATED VARIATIONS OF FREE AMINO ACID EXCRETION LEVELS IN NORMAL ADULTS

Abstract

The authors have been studying the significance of free amino acids in urine on the formation of calculi in the upper urinary tract. Since the epidemiological research on urinary calculi revealed that the formation of calculi depended on sex and age, in this study the excreted amounts of free amino acids in urine were determined and compared as to sex and age on 47 normal adults (30 males and 17 females), and also the factors contributing to the difference of the excreted amounts of free amino acids in urine were discussed.
The results are as reported below.
From female subjects, urine was collected in the non-pregnant period and at the almsot midst between the menstruations.
1. Difference in the 24-hour excretion as to sex and age
(1) In general, the excretion was more in the female, and particularly the excreted amounts of asparagine, glutamine and glycine were significantly larger in the female than in the male.
(2) Concerning the change of the excreted amount of the total amino acid depending on age, it was at the peak in the 30's of age in both the male and the female, and rapidly decreased after the 50's in the male, while it did not tend to decrease so rapidly in the female as in the male. The respective amino acids tended to decrease remarkedly in the males older than 50 years of age, and particularly, the excreted amounts of taurine, aspartic acid, serine, glutamic acid, glutamine, glycine, alanine, cystine, valine, leucine, tyrosine, phenylalanine, ethanolamine, and histidine decreased greatly.
2. Factors determining the personal difference in excreted amounts of amino acids (1) The excreted amount of the total amino acid was positively correlated to the excreted amounts of creatinine and urea nitrogen and the 24-hour endogenous creatinine clearance value, and particularly the individual difference of the total amino acid seemed to depend greatly on the renal clearance value.
(2) Considering the factors for the personal difference, the excreted amount of each amino acid was divided by the 24-hour endogenous creatinine clearance value and the obtained quotients were compared with each other; they were seldom different with respect to age in both the male and female, but when comparing them between the male and female, asparagine and glycine were significantly more in the female than in the male.
According to the above-described results, the excretion of free amino acids in mine appeared to be obviously different with respect to sex in the adult, and particularly the difference of the glycine excretion with respect to sex was very interesting in the aspect of the formation of urinary calculus, since glycine is considered to be related to the metabolism of oxalic acid.