Amino acids in CSF and plasma in hyperammonaemic coma due to arginase1 deficiency.
We report the CSF and plasma amino acid concentrations and their ratios in a male patient with arginase1 deficiency with an unusual early presentation at 34 days of age. He developed hyperammonaemic coma (ammonia >400 μmol/L; normal <90 μmol/L) on postnatal day 35. CSF and plasma concentrations were assayed by ion-exchange chromatography on day 36. Arginine was increased both in plasma (971 μmol/L; controls (mean ± 2SD) 50 ± 42) and in CSF (157 μmol/L; controls 19 ± 8.6), resulting in a normal CSF/plasma ratio of 0.16 (controls 0.41 ± 0.26). Interestingly, glutamine was disproportionately high in CSF (3114 μmol/L; controls 470 ± 236) but normal in plasma (420 μmol/L; controls 627 ± 246); the ratio exceeded unity (7.4; controls 0.76 ± 0.31). The CSF/plasma ratios of most neutral amino acids were elevated but not those of the imino- and of the dibasic amino acids lysine and ornithine. The mechanism leading to the increase of most neutral amino acids in brain is not known.


CONCLUSIONS
A normal glutamine in plasma does not exclude an increased concentration in CSF; it could be useful to ascertain by MRS that a high CSF glutamine concentration truly reflects a high concentration in brain tissue for better understanding its pathogenesis.
Scholl-Bürgi
S
S
Department of Pediatrics, Neuropediatrics and Inherited Metabolic Disorders, Innsbruck Medical University, Innsbruck, Austria. sabine.scholl-buergi@uki.at
Sigl
S Baumgartner
SB
Häberle
J
J
Haberlandt
E
E
Rostásy
K
K
Ertl
C
C
Eichinger-Öttl
U
U
Heinz-Erian
P
P
Karall
D
D
D000328:Adult; D000596:Amino Acids / Q000097:blood* / Q000134:cerebrospinal fluid*; D000641:Ammonia / Q000097:blood*; D001120:Arginine / Q000097:blood / Q000134:cerebrospinal fluid; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D002852:Chromatography, Ion Exchange; D003128:Coma / Q000097:blood / Q000134:cerebrospinal fluid / Q000209:etiology*; D005973:Glutamine / Q000097:blood / Q000134:cerebrospinal fluid; D006801:Humans; D022124:Hyperammonemia / Q000097:blood / Q000134:cerebrospinal fluid / Q000209:etiology*; D020162:Hyperargininemia / Q000097:blood / Q000134:cerebrospinal fluid / Q000150:complications*; D008239:Lysine / Q000097:blood / Q000134:cerebrospinal fluid; D008297:Male; D009952:Ornithine / Q000097:blood / Q000134:cerebrospinal fluid
D000596:Amino Acids; D015415:Biomarkers; D005973:Glutamine; D000641:Ammonia; D001120:Arginine; D009952:Ornithine; D008239:Lysine