Measurement of serum total LDH activity has proved to be a useful means of following
the course of variety diseases.
An elevated serum total LDH activities, however, is in itself of limited value in
establishing the specific site of tissue damage because of the wide distribution of the
enzyme.
Electrophoretic studies of the isoenzyme of serum and tissue LDH can provide more
specific information to the diagnosis of specific organ injury.
By electrophoresis, five distinct bands of LDH are separated, with LDH1
(heart fraction) migrating the most rapidly to anode, LDH5 (liver fraction)
migrating the most slowly to cathod and LDH2-4 migrating between
LDH1 and LDH5. Authors have studied for obtaining of
normal value of serum total LDH activity and LDH isoenzyme by agarose gel
electrophoretic procedure in healthy Koreans(186 cases).
The following results are obtained.
1) Normal value of serum total LDH activity and quantitated percentage of LDH
isoenzyme in Korean male and female are 221.0±138.0(±2SD) unit and
LDH2=36.6±7.2(±2SD)%>LDH1=3l,0±5.2(±2SD)%>LDH>3=27.0±7.6(±2SD)%>LDH4=4.7±4.6(±2SD)%>LDH5
=0.9±2.0(±2SD)% in decreasing order.
2) Serum total LDH activity and quantitated percentage of LDH isoenzyme according to
age and sex have no significant difference.
3) After storage of serum at room temperature, 4℃ and -20℃ because of the
LDH4,5 fraction has low stability. The serum total LDH activity is not
significant, but the LDH5 fraction is not defected in 2 cases of 7 cases
after 4℃ storage and in 5 cases of 7 cases after -20℃ storage.
4) Reproducibility of serum LDH isoenzyme is within ±2SD range.
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