Urinary Excretion of Free Amino Acids in Normal Healthy Females

Urinary Excretion of Free Amino Acids in Normal Healthy Females (mg/24-hr collection) 

Amino acid Single value 8 Range -/ Average  

In regard to the urinary excretion of other free amino acids than histidine during normal pregnancy, the situation is as follows. There is hyperexcretion of glycine, glutamine (including glutamic acid), serine, 

In children above 2 years of age, the situation is not substantially different from adults as far as the relative amounts of amino acids excreted are concerned. In fact, only very few really satisfactory data have been obtained so far in urines from children above 2 years of age. We present therefore in Fig. 3 a typical chromatogram of a 24-hr specimen of urine of a normal child, 2 years old, as drawn from Vis observations. Comparison of quantitative data concerning daily excretions are rendered difficult because of the differences in body size. The 24-hr basis alone is not suitable. It is necessary to compare data on the basis of percentage of total nitrogen excretion, or per kilogram of body weight, a procedure adopted by Jonxis and Huisman. We do not believe it suitable or safe to choose a comparison factor based on creatinine excretion. 

In early infancy the situation is known to be quite different from that among older children. Simon noticed in 1911 that the newborn infant excreted 10 % of its total nitrogen output in the form of amino nitrogen, whereas in adults it drops to 2 % (S15). This was confirmed in later years (B4, Cll, G5) and extended to the study of individual amino acid excretion by microbiological methods (S10, Sll), by paper chromatography (S20, S21), and finally by ion exchange column chromatography (D28, D30) at the time Moore and Stein s first method of 1951 was still the only one available. 

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