[Parenteral administration of amino acids. Reference values--study technic--interpretation of the study results--amino acid pattern as a criterion of the regulation of homeostasis].

The concentrations of free amino acids were measured in lithium-heparinat-plasma with a standardized quality controlled analytical procedure in 200 healthy persons (blood donors). The distribution of the measured values were statistically evaluated in the total group and differentiated in the male and female subcollective. The absolute total concentrations of the free amino acids vary in a broad range between 1.7 and 4.4 mmol/l. This large range is also seen for the single amino acid. In a new system for documentation and interpretation of analytical data the measured values are collected and mean, median, standard deviation, mini-max-range and 95% confidence interval are automatically computed. On this basis of data a physiological reference range is defined. The broad variability of the absolute concentrations is not found in the relative composition of the pattern. The relations of the amino acid concentrations which are important for the quality of the cellular support are very constant. Their importance is caused by the fact that only few different transport systems exist for at least 20 amino acids, which means that the different amino acids are competing at the same system for cellular uptake. The essential of the results in this study is that the liver guarantees the constancy of the physiological pattern also in cases where the exogenous supply differs from the characteristics of elimination of the single amino acid from blood. Only when the oxidative capacity of the liver is insufficient as in pathological states like infections pathological concentrations are found. In these cases the true change is undiscovered when the absolute concentrations are considered, because the insufficient functions of the liver causes initially high total concentrations. For the interpretation of an analysis of amino acids in blood plasma two main criteria are necessary: the total concentration of amino acid characterizes the quantitative support while the concentration pattern determines the quality of the cellular uptake.