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Hepatic phenylalanine metabolism measured by the [ 13 C]phenylalanine breath test
Author(s) -
Kobayashi T.,
Kubota K.,
Imamura H.,
Hasegawa K.,
Inoue Y.,
Takayama T.,
Makuuchi M.
Publication year - 2001
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1046/j.1365-2362.2001.00803.x
Subject(s) - phenylalanine , indocyanine green , breath test , excretion , medicine , gastroenterology , chemistry , amino acid , endocrinology , surgery , biochemistry , helicobacter pylori
Background The amino acid clearance test including phenylalanine is known to reflect liver functional reserve, which correlates with surgical outcome; however, the procedure is not clinically useful because of its laborious and time‐consuming nature. This study evaluates whether phenylalanine oxidation capacity measured by a breath test could reflect liver functional reserve. Design We determined phenylalanine oxidation capacity in 42 subjects using the l ‐[1‐ 13 C]phenylalanine breath test (PBT). The 13 CO 2 breath enrichment was measured at 10‐min intervals for 120 min after oral administration of 100 mg of l ‐[1‐ 13 C]phenylalanine. Subjects were divided into the following three groups according to their plasma retention rate of indocyanine green at 15 min (ICG R15): Group I (ICG R15 < 10%), Group II (ICG R15 10–20%), and Group III (ICG R15 > 20%). First, we determined the parameters of the phenylalanine oxidation capacity that differentiated these groups and then, using these parameters, we compared the PBT with the ICG clearance test, Child–Pugh classification score and standard liver blood tests. Results The % 13 C dose h −1 at 30 min and cumulative excretion at 80 min were significantly different among the three groups ( P < 0·05). These two parameters significantly correlated with the ICG R15, Child–Pugh classification score ( P < 0·0001) and results of standard liver blood tests ( P < 0·05). Conclusions Phenylalanine oxidation capacity measured by the PBT was reduced according to the severity of liver injury assessed by the ICG clearance test, Child–Pugh classification, and standard liver blood tests. These results indicate that the PBT can be used as a noninvasive method to determine liver functional reserve.