Delta-Aminolevulinic Acid, Random Urine

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Category:

Turnaround Time: 2 - 4 days
CPT Code:

82135

Test Type: 3 mL aliquot Urine (random)
Stability Time:

Freeze immediately and protect from light. Note: Urine is not stable preserved with sodium carbonate. It is stable for one month when preserved with 30% acetic acid and frozen (-20°C to 0°C), or stable for three days with 30% acetic acid when refrigerated (2°C to 8°C).

Reference Range:

0.0-5.4 mg/L

Overview:

Diagnose porphyrias: Δ-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 Δ-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 of <15 μg/dL. ALA is increased also in tyrosinemia.1,2 Porphobilinogen and δ-aminolevulinic acid are the tests of choice for acute intermittent porphyria. Recently the molecular lesions have been identified in a severely affected homozygote with δ-aminolevulinate dehydratase deficient porphyria.3ALA 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. A 24-hour urine collection may provide more clinically representative data (see Δ-Aminolevulinic Acid, 24-Hour Urine [096354]).

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the Food and Drug Administration.

Conversion of ALA to porphobilinogen is inhibited by lead and mercury; thus, lead poisoning causes increased urinary Δ-ALA, as well as increases of coproporphyrin and of free erythrocyte protoporphyrin.

1. Labbe RF, Lamon JM. Porphyrins and disorders of porphyrin metabolism. In: Tietz NW, ed. Fundamentals of Clinical Chemistry. 3rd ed. Philadelphia, Pa: WB Saunders Co;1987:825-841.

2. Hereditary tyrosinaemia. Lancet. 1990 Jun 23; 335(8704):1500-1501. PubMed 1972437

3. Plewinska M, Thunell S, Holmberg L, et al. ?-Aminolevulinate dehydratase deficient porphyria: Identification of the molecular lesions in a severely affected homozygote. Am J Hum Genet. 1991 Jul; 49(1):167-174. PubMed 2063868

Collection Details:

Collection Instructions:

Plastic urine container with 0.5 mL of 30% acetic acid and amber plastic frozen transport tube and cap (LabCorp No. 78656).

On collection of random urine, it is advisable not to use first voided morning specimen, late evening specimen after 8 PM, or specimen obtained following excessive fluid intake. pH must be <6. Transfer the urine into a LabCorp amber plastic frozen transport tube with amber cap (LabCorp No. 78656). Label the container with the patient's name and date. The specimen should be frozen immediately and maintained frozen until tested. (If amber tube and cap are not available, cover a clear plastic transport tube completely from top to bottom with aluminum foil. Identify the specimen with the patient's name directly on the transport tube and the outside of the aluminum foil. Secure with tape.)

Freeze immediately and protect from light. Note: Urine is not stable preserved with sodium carbonate. It is stable for one month when preserved with 30% acetic acid and frozen (-20°C to 0°C), or stable for three days with 30% acetic acid when refrigerated (2°C to 8°C).