Proline

Proline is an amino acid, a building block of proteins, and is especially important for collagen, the structural protein found in skin, bone, and connective tissues. This test measures the amount of proline in your blood or urine as part of an amino acid profile.

Clinicians use the result to see how your body makes and breaks down proline and how your kidneys and liver handle it. Depending on the clinical question, the test may be performed on a fasting plasma sample or on urine, and it is interpreted together with other amino acids and your clinical history.

Abnormal proline levels can point to inherited conditions that affect proline metabolism, sometimes called hyperprolinemias. Levels can also shift with kidney or liver disease, severe illness, high intake of collagen or amino acid supplements, or inadequate protein intake.

Your clinician may order this test to evaluate seizures, developmental concerns, connective tissue problems, or unexplained neurologic symptoms, and to assess nutritional or metabolic status. Results can help guide diet, monitoring, and when appropriate, genetic evaluation and counseling.

Interpretation depends on your age, the sample type, and how the specimen was collected. A result outside the laboratory reference interval does not by itself diagnose a disorder. Your clinician will review the pattern of amino acids, kidney and liver markers, medications, and your symptoms before making decisions.

If results are unexpected, the test may be repeated under fasting conditions or collected as a timed or first morning urine. You may be asked about diet, supplements, and medicines. In some situations, additional metabolic studies or genetic testing are recommended. Avoid changing supplements or diet without medical advice.