Table 1.

Plasma Ammonia Concentrations Observed in HHH Syndrome by Age of Diagnosis

Plasma Ammonia Concentration in µmol/L by Age of Diagnosis 1
Neonatal (birth – 1 mo) (n=6)Infantile (>1 mo – 1 yr) (n=5)Childhood (>1 yr – 12 yrs) (n=36)Adolescence to Adulthood (>12 yrs) (n=17)Total (n=64)
Median300173120117136
Mean560577160119219
SD50796512169339
Range111-130049-230025-53218-25018-2300

SD = standard deviation

1.

The upper limit of normal plasma ammonia can vary among laboratories. Values of 40 μmol/L or less are usually considered normal for most infants, children, and adults; however, the upper limit of normal in neonates is 100 μmol/L (see Argininosuccinate Lyase Deficiency).

From: Hyperornithinemia-Hyperammonemia-Homocitrullinuria Syndrome

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