Aminolevulinic Acid, Delta, 24-Hour Urine
| Aminolevulinic Acid, Delta, 24-Hour Urine | | | |
| Number | | 096354 |
| CPT | | 82135 |
| Related Information | | Porphyrins, Quantitative, Random Urine Urine Testing: Preservative Quick Reference Chart |
| Synonyms | | ALA, 24-Hour Urine ; Delta-ALA, 24-Hour Urine ; Delta Aminolevulinic Acid, 24-Hour Urine |
| Special Instructions | | Measure and record total 24-hour urine volume on the request form. Use test 007351 for random urine. |
| Specimen | | Urine (24-hour), frozen and protected from light |
| Volume | | 25 mL aliquot |
| Minimum Volume | | 1 mL aliquot |
| Container | | Plastic 24-hour urine container with 30 mL of 30% glacial acetic acid. Use amber plastic urine cup and amber top; order LabCorp No 20656. (If amber cups are unavailable, cover plastic container completely, top and bottom, with aluminum foil. Identify specimen with patient name directly on the container and on the outside of the aluminum foil. Secure with tape.) |
| Collection | | Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Measure and record total 24-hour urine volume on the request form. Mix well. pH must be <6. |
| Storage Instructions | | Freeze immediately and protect from light. Note: Urine is not stable preserved with sodium carbonate. It is stable for 1 year when preserved with 30% glacial acetic acid and frozen (-20°C to 0°C), or stable for 4 months with 30% glacial acetic acid when refrigerated (2°C to 8°C). |
| Causes for Rejection | | pH not <6; specimen not protected from light; use of preservative other than 30% glacial acetic acid; use of sodium carbonate preservative |
| Reference Interval | | 1.5-7.5 mg/24 hours |
| Use | | Diagnose porphyrias: delta-ALA may be increased in attacks of acute intermittent porphyria, hereditary coproporphyria, and porphyria variegata; evaluation of certain neurological problems with abdominal pain; diagnosis of lead or mercury poisoning. Urinary delta-ALA is not a sensitive indicator of lead poisoning in children because it does not increase until blood lead concentration is 40 μg/dL, well above the recommended level <15 μg/dL. ALA is increased also in tyrosinemia.1,2 Porphobilinogen and delta aminolevulinic acid are the tests of choice for acute intermittent porphyria. Recently the molecular lesions have been identified in a severely affected homozygote with delta aminolevulinate dehydratase deficient porphyria.3 |
| Limitations | | ALA may be normal during latent period of acute intermittent porphyria, hereditary coproporphyria, porphyria variegata. For the diagnosis of lead poisoning, measurement of blood and urine lead, and free erythrocyte protoporphyrin are other available options. |
| Methodology | | Column chromatography; Ehrlich reagent - spectrophotometry |
| Additional Information | | Conversion of ALA to porphobilinogen is inhibited by lead and mercury; thus, lead poisoning causes increased urinary delta-ALA, as well as increases of coproporphyrin and of free erythrocyte protoporphyrin. |
| Footnotes | | - Labbe RF and Lamon JM, “Porphyrins and Disorders of Porphyrin Metabolism,” Fundamentals of Clinical Chemistry, 3rd ed, Tietz NW, ed, Philadelphia, PA: WB Saunders Co, 1987, 825-41.
- “Hereditary Tyrosinaemia,” Lancet, 1990, 335(8704):1500-1.
- Plewinska M, Thunell S, Holmberg L, et al, “Delta Aminolevulinate Dehydratase Deficient Porphyria: Identification of the Molecular Lesions in a Severely Affected Homozygote,” Am J Hum Genet, 1991, 49(1):167-74
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