FREE AMINO ACIDS OF BLOOD AND URINE 231 
seems to be some link between urinary output of this amino acid and that of creatine. 
During all the time when there is a urinary creatine output, 7.e. before the age of 
puberty, there is a rather low excretion of 3-methylhistidine. When this critical 
period of life is over, creatinuria disappears and urinary output of 3-methylhistidine, 
as well as that of taurine, tends to be elevated (Dr. H. Vis!"). 
The case of lysine excretion is difficult to interpret owing to our present state of 
knowledge. In fact it is very surprising to observe that in infants 9 months—2 years 
23%) 
AVERAGE EXCRETIONSIN % OF TOTAL OF AVERAGE FIGURES. 
20% 4 
i ADULTS (Both sexes: 6 males +9 females) 
CHILDREN (Both sexes: 8 boys +7 girls ) 
YEO (Age range: 9 months to 2 years) 
10% 4 

5 th - 

=) AS) a) a en x oO <t L L oFes = 7) (‘yes <5 Dm c 
= ~w =a 35 oS ° so = co ta = le ° is} > Sey ud oe ter S =< > = 
oO = ae z = = < a Fe FR i —I Oe Na) > <a <q >= < Oo 
202 mn o a“ a s 
5 = = 
Fig. 3. Aminoaciduria in normal adults and normal children. Average excretion in percents of 
total average figures. Notice that the situation in children and adults is different. 
old the excretion of lysine is relatively much higher than it is in adults, when one 
takes into account that specific needs for this indispensable amino acid are so im- 
portant for growth. 
It has been demonstrated very recently (April 1961) that homocitrulline is a 
normal constituent of children’s urine®®. 
Normal free amino acid levels in plasma 
Qualitative composition. A typical elution curve obtained by the MooRE AND STEIN 
1954 manual procedure from deproteinized human blood plasma will be found in 
a paper by SoupartT®. Fig. 4 shows the automatically recorded elution curve ob- 
tained in our department by use of the SPACKMAN, MOORE AND STEIN automatic 
procedure!!! which is in complete agreement with that published by these authors!™. 
Although Fig. 4 represents the free amino acid composition of plasma in an 
untreated leukemic patient, it is given here for the same reasons as Fig. 1. When 
compared with urine amino acid composition, the free amino acid composition 
References p. 261/262 
