Free amino acids, copper, iron and zinc composition in sera of patients with thyrometabolic diseases.

Free amino acids together with copper, iron and zinc were measured in sera of 67 adult patients with thyrotoxicosis (n = 29) or hypothyroidism (n = 38). In contradistinction to the almost indifferences exhibited by the three metals, many amino acids displayed significant relationships with the thyrometabolic activity (mainly tyrosine and arginine with r values of 0.5 and 0.44, respectively). Additional analyses revealed certain patterns, between trace metals and amino acids, which conferred challenging difficulties to interpretation. Thus while zinc was associated positively with some amino acids (such as glutamic acid and alanine), copper correlated almost invariably in a negative manner with citrulline, alpha-amino-butyric acid, proline, glycine and valine. This new information should contribute to our knowledge of the complex metabolism of both trace metals and amino acids.