[Diurnal variations of human serum amino acid concentration]

In 5 healthy persons, as well as in 9 hospitalized patients with Parkinsonism and without metabolic disorders, diurnal variations of the concentrations of amino acids are determined in blood serum. It has been found that in addition to the peaks due to the digestion after meals, another peak in concentrations appeared. This peak was found between 2 and 4 a.m. and did not appear simultaneously for all amino acids. During this time, the urinary excretion of amino acids was also high.