L-Tyrosine is a conditionally essential amino acid.1 It is produced by hydroxylation of phenylalanine by phenylalanine hydroxylase but can also be obtained from dietary sources or degradation of endogenous proteins, resulting in L-tyrosine release.1,2 L-Tyrosine is a precursor in the biosynthesis of catecholamine neurotransmitters, melanins, and thyroid hormones.3 Plasma, skeletal muscle, and erythrocyte levels of L-tyrosine are decreased in patients with chronic kidney disease.1
References:
[1]. Kopple, J.D.Phenylalanine and tyrosine metabolism in chronic kidney failureJ. Nutr.137(6 Suppl 1)1586S-1590S(2007).
[2]. Webster, D., and Wildgoose, J.Tyrosine supplementation for phenylketonuriaCochrane DB Syst. Rev.6CD001507(2013).
[3]. Slominski, A., and Paus, R.Towards defining receptors for L-tyrosine and L-DOPAMol. Cell Endocrinol.99(2)C7-C11(1994).