tyrosinemia /tī′rōsinē″mē·ə/ [Gk, tyros + haima, blood] , 1. a benign, transient condition of the newborn, especially premature infants, in which an excessive amount of the amino acid tyrosine is found in the blood and urine. The disorder is caused by an anomaly in amino acid metabolism, usually delayed development of the enzymes necessary to metabolize tyrosine. It is controlled by dietary measures and vitamin C therapy. The metabolic defect disappears with treatment, or it may disappear spontaneously. Also called neonatal tyrosinemia. 2. a hereditary disorder involving an inborn error of metabolism of the amino acid tyrosine. The condition, which is transmitted as an autosomal-recessive trait, is caused by an enzyme deficiency and results in liver failure or hepatic cirrhosis, renal tubular defects that can lead to renal rickets and renal glycosuria, generalized aminoaciduria, and cognitive impairment. Treatment consists of a diet low in tyrosine and phenylalanine and high in vitamin C. In severe cases prognosis is extremely poor, and a liver transplantation may be the only lifesaving measure. Also called hereditary tyrosinemia.
