A urea cycle disorder can present in the older child, adolescent or adult as well as in the neonate. Certain findings should trigger consideration of this as a possible diagnosis for a patient with unexplained signs and symptoms.


Clues that may indicate the presence of a urea cycle disorder:

(1) family history of a metabolic disorder, especially if there is an autosomal recessive pattern of inheritance or a history of consanguinity

(2) family history of infant mortality

(3) avoidance of protein in diet, with high carbohydrate intake or vegetarianism

(4) unexplained anorexia, cyclic vomiting, feeding problems or food intolerance

(5) history of frequent illnesses during childhood

(6) history of routine health problems resulting in severe illness and/or a prolonged clinical course

(7) history of psychiatric or behavioral problems, including agitation or disorientation

(8) unexplained encephalopathy

(9) unexplained lethargy

(10) altered level of consciousness (somnolent, coma)

(11) chronic neurological problems (recurrent headaches, ataxia, seizures, etc)

(12) recurrent noninfectious hepatitis

(13) elevated blood ammonia level


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