CSF Tyrosine

This test measures the amount of tyrosine, an amino acid, in your cerebrospinal fluid (CSF). CSF surrounds your brain and spinal cord, so its composition can reflect what is happening in the central nervous system more directly than a blood test.

Doctors may order CSF tyrosine as part of a broader amino acid profile when evaluating neurologic symptoms or suspected metabolic conditions. The sample is collected during a lumbar puncture and handled under specific laboratory conditions to preserve amino acids for accurate analysis.

Tyrosine levels in CSF can provide clues about how your body processes certain amino acids and how well these substances move between the blood and the brain. Abnormal levels can be seen with inherited metabolic conditions that affect tyrosine pathways, with disorders that change amino acid transport into the brain, or as an effect of specific treatments.

Your clinician might order this test if you have unexplained seizures, developmental concerns, movement disorders, or other neurologic changes, especially when a metabolic cause is being considered. Results are interpreted alongside plasma amino acids, urine studies, imaging, and your clinical history to guide diagnosis and treatment.

If your CSF tyrosine is higher than expected, your clinician will consider medications, diet, and underlying liver or metabolic conditions, and will also check whether the sample was contaminated with blood. If it is lower than expected, transport problems across the blood brain barrier, nutritional issues, or other metabolic disorders may be considered.

Most of the time, this test is one piece of a larger evaluation. Your care team may repeat the test if the sample was difficult to collect, review your current medications and supplements, and order additional studies such as a full CSF amino acid profile, plasma amino acids, or genetic testing. Discuss any questions with your clinician so you understand what the results mean for you and what steps come next.