Histidine concentration in cerebrospinal fluid (CSF)

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like headaches, neurological issues, or if they suspect a metabolic disorder, genetic condition, or other neurological problem that could involve abnormal amino acid levels in CSF. It may also be part of a broader evaluation for conditions like urea cycle disorders or other inborn errors of metabolism.

What to Expect Before the Test

You’ll likely have a lumbar puncture (spinal tap) to collect CSF. This involves lying on your side, having a local anesthetic injected, and then a small needle being inserted into your lower back to draw fluid. You may feel pressure or a slight ache afterward, but it’s generally quick and well-tolerated. Avoid heavy lifting or strenuous activity for 24 hours before the procedure.

What the Test Results Mean

Results are interpreted by your healthcare provider based on your symptoms, medical history, and other test results. Abnormal levels might indicate metabolic issues, genetic disorders, or other neurological conditions that require further evaluation.

Common Conditions Monitored

While histidine in CSF isn’t as commonly monitored as other metabolites, elevated or low levels may be associated with rare genetic disorders affecting amino acid metabolism, such as histidinemia or urea cycle defects. It can also be part of broader metabolic screening in newborns or children with suspected inborn errors of metabolism.