Tyrosinemia type 3 (Orphanet rare-disease nomenclature term Orphanet_69723) is an inborn error of tyrosine metabolism characterised by mild hypertyrosinemia and increased urinary excretion of 4-hydroxyphenylpyruvate, 4-hydroxyphenyllactate and 4-hydroxyphenylacetate. Also known as: Tyrosinemia due to 4-hydroxyphenylpyruvate dioxygenase deficiency, Tyrosinemia due to 4-hydroxyphenylpyruvic acid oxidase deficiency, Tyrosinemia due to HPD deficiency, Tyrosinemia type III.