Description

Tyrosine is a nonessential amino acid that derives from dietary sources, the hydroxylation of phenylalanine, or protein breakdown. Primary (PKU) and secondary (defects of BH4 metabolism) hyperphenylalaninemia can cause abnormally low levels of tyrosine. Measurement of the phenylalanine:tyrosine ratio is helpful in monitoring appropriate dietary intake. TYROSINE Premature: 147-420 nmol/mL 0-31 days: 55-147 nmol/mL 1-24 months: 22-108 nmol/mL 2-18 years: 24-115 nmol/mL > or =19 years: 34-112 nmol/mL

Pre-Information

Clinical history, suspicion of metabolic diseases or inborn errors of metabolism, fasting recommendation but not mandatory, and preliminary diagnosis of the clinician are all necessary.