[Determination of delta-aminolevulinic acid dehydratase in venous and capillary blood and delta-aminolevulinic acid in urine of lead-exposed workers].

Delta-aminolaevulinic acid dehydrogenase is a key enzyme in porphyrin synthesis which catalyses the formation of porphobilinogens from two molecules of delta-aminolaevulinic acid. Delta-aminolaevulinic acid dehydratase is a sulphhydryl group enzyme which is inhibited by lead ions and other heavy metal ions. A method has been devised on that basis to determine industrial and ecological lead intoxication. While correlations have been statistically secured between airborne lead concentration, biochemical reactions, inhibition of delta-aminolaevulinic acid dehydratase, and increased discharge of delta-aminolaevulinic acid, determination of enzyme activity cannot be used in situations of high exposure to lead, because inhibition was found to be too strong, and dose-action relationship between actual exposure and biological response were found to provide no information with relevance to industrial medicine. A method less sensitive than determination of delta-aminolaevulinic acid should be preferred for monitoring of higher lead concentrations. Determination of delta-aminolaevulinic acid dehydratase activity is applicable only to low or usual lead exposure.