Urinary 5-aminolevulinic acid (ALA) adjusted by creatinine: A surrogate for plasma ALA?

Pornchai Sithisarankul, Brian S. Schwartz, Byung Kook Lee, Paul T. Strickland

Research output: Contribution to journalArticlepeer-review

Abstract

5-Aminolevulinic acid (ALA) is the first intermediate substrate in the heme synthetic pathway and is the substrate of aminolevulinic acid dehydratase (ALAD, porphobilinogen synthase). Because lead effectively inhibits ALAD activity, resulting in accumulation of ALA in urine and blood, urinary ALA (ALAU) has been used as a biomarker for lead exposure or early biologic effect of lead. Intraindividual variation in urinary excretion of ALA requires the use of 24-hour urine samples on adjustment of single urine samples by other normalizing variables, such as urinary creatinine concentration. Previous studies of ALAU concentration have used various adjustment methods; however, few have compared creatinine-adjusted ALAU concentration with ALA concentration in plasma (ALAP) from subjects with low (< 30 μg/dL) to moderate (< 60 μg/dL) levels of blood lead. To determine if creatinine-adjusted ALAU is associated with ALAP, we measured ALAU, ALAP, and urinary creatinine in 65 Korean lead workers with blood lead concentrations in the range of 14-60 μg/dL ALAU, ALAU/creatinine, or ALAU/log creatinine all correlated with ALAP. However, ALAU/creatinine correlated more closely with ALAP based on Spearman's r (r(s) = 0.40, P = 0.0009), supporting the use of ALA/creatinine in single urine samples as a surrogate for ALAP.

Original languageEnglish (US)
Pages (from-to)901-906
Number of pages6
JournalJournal of occupational and environmental medicine
Volume40
Issue number10
DOIs
StatePublished - Oct 1998

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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