5-AMINOLAEVULINATE - urine

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Specimen: Random urine.

Method: Spectrophotometry.

Reference Interval:

<3.8 mmol/mol creatinine

<40 mmol/L

Application: Diagnosis of acute neurological porphyrias during an acute episode, however urine porphobilinogen is the preferred test, except for plumboporphyria. Limited value in the diagnosis of lead poisoning; the test is less sensitive than blood lead and may be negative in organic lead poisoning (leaded petrol).

Interpretation: Increased levels are found during acute attacks of acute intermittent porphyria, hereditary coproporphyria, porphyria variegata and plumboporphyria. In inorganic lead poisoning, porphobilinogen synthetase is inhibited, resulting in increased levels of 5-aminolaevulinate. However, the test does not reliably detect lead exposure in the distant past as, with time, lead is sequestered in bone. The test is also unreliable in patients with very recent exposure to organic lead, eg petrol sniffing. Increased levels are found in patients with type 1 tyrosinaemia.

Reference: Thunell S et al. J Clin Chem Clin Biochem 1987; 25: 5-14.

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