Tyrosine

This test measures tyrosine, an amino acid that your body uses to build proteins and make important molecules such as thyroid hormones, dopamine, and melanin. Tyrosine is made from phenylalanine and is normally kept within a narrow range by the liver and other tissues.

Your clinician may check tyrosine in blood, urine, or both. It is often included in an amino acid profile to evaluate how your body processes proteins. Results help identify metabolic conditions, guide nutrition plans, and monitor certain treatments.

Tyrosine levels can provide clues about how well your body breaks down amino acids and how your liver is functioning. High levels can be seen in inherited conditions such as tyrosinemia, in temporary situations in newborns, or with liver disease. Low levels can occur with poor intake, malabsorption, or certain dietary treatments. For people treated with nitisinone for tyrosinemia type 1, monitoring tyrosine helps balance effective therapy with the risk of eye or skin symptoms.

Your clinician may order this test if there are symptoms such as poor growth, liver problems, eye irritation, learning concerns, or after an abnormal newborn screen. It is also used to follow specialized diets or medications and to assess recovery from illness that affects protein metabolism.

Interpreting tyrosine depends on your age, the type of sample, and your overall health. Babies and young children can have different typical levels than adults, and urine results are often reported relative to creatinine, which reflects how concentrated the urine is. Your clinician will usually look at other amino acids, especially phenylalanine, and sometimes additional markers such as succinylacetone to understand the full picture.

If your result is slightly outside the expected range, your care team may repeat the test, adjust timing to a fasting sample, or review your diet, supplements, and medicines. Persistently high or low levels may prompt more testing, such as a comprehensive amino acid profile, liver evaluation, or genetic consultation. Do not change your diet or medicines on your own; discuss any result with your clinician, who will advise on next steps based on your situation.