Fractionation of serum gamma-glutamyltransferase (γ-GT)

【要約】
Fractionation of serum gamma-glutamyltransferase (γ-GT) by
high performance gel filtration chromatography for differential
diagnosis of γ-GT elevation
（高γ―グルタミルトランスフェラーゼ血症の鑑別診断における高
速ゲル濾過クロマトグラフィーによる分画の有用性）
千葉大学大学院医学薬学府
先進医療科学専攻分子病態解析学
（主任：野村文夫教授）
末吉
茂雄
Background & Aims: Serum gamma-glutamyltransferase (GGT) activity is a useful
marker for hepatic damage in clinical practice, although its specificity for the causes of
hepatic disorders remains unknown. GGT can be separated into 4 fractions according to
molecular weight, but the significance is not fully understood. The aim of this study was
to elucidate whether measuring enzyme activity in the 4 GGT fractions would be useful
for distinguishing hepatic disorders of different etiologies such as alcoholic liver disease
(ALD) and nonalcoholic fatty liver disease (NAFLD).
Methods: Serum samples were collected from 20 subjects with NAFLD, 27 subjects
with ALD, and 10 healthy controls. Serum GGT in each sample was separated into 4
fractions by high-performance gel filtration chromatography, and enzyme activity was
measured in each fraction. Relative proportions of total GGT (t-GGT) activity were
analyzed.
Results: Serum GGT was separated into 4 fractions, including big-GGT (b-GGT),
medium-GGT (m-GGT), small-GGT (s-GGT), and free-GGT (f-GGT). The proportion
of s-GGT activity was significantly increased in subjects with ALD (mean ± SD: 0.65 ±
0.144) compared with that in subjects with NAFLD (0.54 ± 0.085), whereas b-GGT
activities was increased in subjects with NAFLD (b-GGT: 0.20 ± 0.076) compared with
those in subjects with ALD (b-GGT: 0.15 ± 0.080). b-GGT activity in subjects with
NAFLD showed strong correlations with the levels of low-density lipoprotein and
apolipoprotein B, suggesting that b-GGT activity is related to the accumulation of lipid
in the pathogenesis of NAFLD.
Conclusions: This study showed that GGT fraction analysis can be clinically useful for
distinguishing different etiologies in patients with hepatic disorders.
Keywords:
Fractional
gamma-glutamyltransferase;
alcoholic
liver
nonalcoholic fatty liver disease; low-density lipoprotein
Abbreviations used in this paper
GGT, Gamma-glutamyltransferase; ALD, alcoholic liver disease; NAFLD,
nonalcoholic fatty liver disease; t-GGT, total GGT; b-GGT, big-GGT; m-GGT,
medium-GGT, s-GGT, small-GGT; f-GGT, free-GGT; NASH, nonalcoholic
steatohepatitis; CRP, C-reactive protein; HDL, high-density lipoprotein; LDL,
low-density lipoprotein
disease;
Gastroenterology
平成 25 年 12 月 18 日
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