Simple screening test for qualitative detection of increased delta-aminolevulinic acid in urine.

Abstract

Abstract A simple qualitative procedure for demonstrating increased delta-aminolevulinic acid (ALA) in urine is needed to identify individuals with an inherited deficiency of the enzyme ALA dehydratase, a newly described porphyria-like syndrome. The present procedure includes two steps, the last of which is carried out only on samples that are positive in the first step. Urine is tested for pyrroles, preformed or formed by heating with acetylacetone, by looking for a pink color after p-dimethylaminobenzaldehyde is added. Samples showing the color are next tested for ALA by adsorbing natural pyrroles onto Dowex-1 in sodium acetate, heating the supernate with acetylacetone, adsorbing the resulting aminoketone pyrroles onto Dowex-1 in water, separating the ALA from other aminoketones by differential extraction, and again looking for a pink color with p-dimethylaminobenzaldehyde. Positive urines, those with concentrations of ALA greater than or equal to 10-15 mg/L, yield a pink color in each step. Samples with greater than 30 mg/L ALA show a magenta color. Aminoacetone in excess of 3 mg/L ALA also yields a pink color, but such a concentration in urine is unlikely. Many samples can easily be tested concurrently.