Abnormal urine metabolite level Elevated urinary succinylacetone level 2024-03-18T20:19:37Z As a result of the metabolic block in tyrosinaemia type 1, toxic metabolites are formed including succinylacetone, maleylacetoacetate and fumarylacetoacetate. These are responsible for severe disruption of intracellular metabolism of the liver and kidney. Presence in the urine of succinylacetone, which is one of the toic block metabolites formed in tyrosinaemia type 1 because of a defect in the final enzyme of the pathway of the degradation of tyrosine, namely fumarylacetoacetase (FAH, EC 3.7.1.2).