Synonym: transient neonatal hyperammonemia (TNH)
Risk factors:
(1) premature delivery
(2) asphyxia and/or low Apgar score at birth
(3) large birthweight for gestational age
Clinical features:
(1) neurologic findings (depressed level of consciousness, seizures)
(2) onset of respiratory distress within 24 hours of birth, usually with an abnormal chest radiograph
(3) variable sclerema neonatorum (with hardening of the subcutaneous tissues)
(4) elevated plasma ammonia concentration
(5) elevated liver function tests
(6) normal organic aciduria
(7) normal plasma ammonia levels and improved neurologic status after recovery (although an infant born premature and with asphyxia may have neurologic problems)
(8) exclusion of urea cycle disorders and other hereditary metabolic disorders associated with hyperammonemia
Therapy in severe cases may include:
(1) exchange transfusion
(2) peritoneal dialysis
(3) continuous arteriovenous hemodiafiltration
