The determination of δ-aminolebulinic acid in the urine is used for the laboratory diagnosis and differential diagnosis of porphyria, a group of diseases with signs and symptoms of the skin and nervous system. The measurement of S-aminolebulinic acid in the urine can be used even in laboratory testing of lead poisoning in children.
S-aminolevulinic acid (ALA) is the precursor for portocholinogen (PBG), a substance used in hemoglobin heme formation. The next steps in the biochemical pathway of heme synthesis include: Porphocholinogen → Urocholinogen III ρο Uroporphyrin III → Coproporphyrin III → Coproporphyrin III→ Protoporphyrinogen → Protoporphyrin. This process then leads to the formation of heme. If any problem arises in the biochemical pathway of heme formation, S-aminolevulinic acid accumulates and is excreted in the urine. S-aminolevulinic acid is normally absent in urine.
Concentrations of δ-aminolevulinic acid in urine are significantly increased in many patients with acute neurological forms of porphyria. Screening for S-aminolebulinic acid may be required in patients with symptoms that indicate acute porphyria, such as abdominal pain, nausea, constipation, peripheral neuropathy, muscle weakness, urinary retention, confusion, and hallucinations.
The presence of S-aminolebulinic acid in urine may still indicate lead poisoning. The test can be used as a pre-screening test to detect excessive lead absorption well before symptoms occur, especially in children.
Possible Interpretations of Pathological Values
- Increase: Acute porphyria, alcohol abuse, hepatitis, liver cancer, lead exposure, lead poisoning. Medications: barbiturates, griseofulvin, penicillin, rifampicin.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.