Severe neonatal transient hyperammonemia: a report of two cases and literature review / 中华围产医学杂志

ABSTRACT

Objective:To investigate the clinical features, treatment, and prognosis of transient hyperammonemia of the newborn (THAN).Methods:Data of two infants with severe THAN admitted to the Department of Neonatology of Shanghai Children's Hospital in September 2021 and August 2022 were retrospectively investigated. Clinical data of confirmed THAN cases (blood ammonia>400 μmol/L) were collected from relevant literature retrieved from the Wanfang Database, China National Knowledge Infrastructure, Chinese Medical Journal Database, and PubMed up to July 2022. A descriptive method was used for statistical analysis.Results:A total of 24 cases were involved (two in the present study, and 22 in 12 retrieved articles), including 19 (79.2%) premature newborns and five term infants. The average birth weight was (2 237±608) g and the average onset time was 27 h (4-55 h) after birth. The early clinical symptoms included respiratory distress and hyporesponsiveness (drowsiness, lethargy, coma or hypotonia) in 18 cases (75.0%), metabolic acidosis in 11 cases (45.8%), hypocalcemia in seven cases (29.2%), pupil fixation/dilation in six cases (25.0%), convulsion in five cases (20.8%), apnea in three cases (12.5%) and sinus bradycardia in one case (4.2%). The serum ammonia levels were 1 422.8 μmol/L (547.2-4 494.1 μmol/L). Treatments included peritoneal dialysis plus exchange transfusion in eight cases (33.3%), exchange transfusion in seven cases (29.2%), continuous renal replacement therapy (CRRT) in four cases (16.7%), arginine in two cases (8.3%), peritoneal dialysis in two cases (8.3%), and CRRT+peritoneal dialysis in one case (4.2%). During follow-ups of four months (one month to six years), 13 cases (54.2%) showed no abnormalities in development; two (8.3%) had a neurodevelopmental delay, and six (25.0%) died. The follow-up of the other three cases (12.5%) were not reported in the literature.Conclusions:The early clinical manifestation of severe THAN is atypical. A good prognosis can be expected through early exclusion of possible hyperammonemia-related genetic metabolic diseases and lowering the serum ammonia level. Long-term follow-up is needed for neurological evaluation.