Porphobilinogen synthetase

Keywords: Aminolaevulinate dehydratase

Specimen:

2 mL blood in lithium heparin tube.

Method:

Spectrophotometry.

Reference Interval:

Varies with method: generally 10-26 U/L.

Application:

Decrease in the enzyme has been used as an indicator of increased lead exposure, but this has been largely superseded by measurement of blood lead.

The enzyme is also decreased in the very rare genetic disease, plumboporphyria.

Interpretation:

Inhibition of the enzyme commences with levels of blood lead unlikely to cause acute symptoms.

Plumboporphyria is an autosomal recessive disease with virtual absence of enzyme activity; heterozygotes have about 50% activity.

Reference:

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