AMINO ACIDS IN PRE- AND POST-NATAL PERIODS 271 
healthy infants provided with enough dietary vitamin C. ROBINSON AND SMITH}! 
even claim that “many” adults excrete f-hydroxyphenylpyruvic acid and p-hydroxy- 
phenyllactic acid in considerable amounts under different pathological conditions, 
while GROos AND KIRNBERGER?! found the two acids only in liver disorders. AMMON 
AND HENNING}? detected a small amount of p-hydroxyphenylpyruvate in urine of 
every healthy individual examined. 
B. URINE 
In infancy, as in adulthood, the excretion of amino acid in urine depends, among 
other things, on the following factors: (1) age; (2) nutrition (protein content, fluid 
and vitamins); (3) hormones; (4) function of the liver; (5) function of the kidneys; 
(6) presence of malignant diseases; (7) different poisons; (8) inborn errors of metab- 
olism (see WESTALL’s paper p. 195). 
The simplification in the detection of amino acids achieved by modern methods!4, 
especially paper chromatography!>*? %¢4, has led to a very broad and sometimes non- 
critical use of these procedures in the clinical laboratory. Therefore, published values 
determined by the various methods differ considerably. Additional sources of variation 
are found in the reference values used, such as body weight, volume of 24-h urine 
specimen, total nitrogen, and especially creatine. The creatine index particularly 
should not be used in the first post-natal days, since the excretion of this substance 
shows marked fluctuations. 
1. Age 
PFAUNDLER™®, the famous pediatrician from Munich, discovered (1g00) with an 
inappropriate method the principle of hyperaminoaciduria in young infants. Using 
SORENSEN’s formol titration method, his pupil Stmon!8? showed that newborns 
eliminate up to 10% of the total nitrogen excretion as amino nitrogen. To be sure, 
this value is too high due to procedural limitations. The relationship to the adult urine 
values, however, is principally correct and agrees with the findings of recent years. 
BARLOW AND McCANcE” showed that this ratio is especially high in the first 24 h 
and decreases somewhat in the next few days. This has been confirmed many 
tamaests 7S: 
The amino-nitrogen elimination, expressed in mg/day, increases in the 1st week of 
life approximately parallel to the increase of urine volume!4>-™8, The total elimina- 
tion reaches its maximum at about the 6th week of life. As is evident from Fig. 3, the 
amino-nitrogen/total-nitrogen quotient differs from this trend in that it shows a precipi- 
tous decline about the 14th day of life. In the first few days after birth the amino-N 
elimination in prematures is often lower than, or at least not higher than, that of full- 
term infants. In the ensuing weeks, however, almost all amino acids show an increased 
excretion. This has been reported by GOEBEL® in respect to amino-nitrogen. 
The large quantities of taurine found immediately after birth in the urine of the 
bladder and in the blood of the umbilical cord!*®, are obviously a characteristic of 
fetal metabolism. This can result either from the immaturity of the taurine degra- 
dation mechanism, or from an increased synthesis. On the other hand, it cannot be 
properly explained why taurine is excreted by full-term infants in greater quantity 
than by prematures. The large range of variation of lysine and cystine excretion in 
References p. 279/283 
