Discussion
The findings of our meta-analysis suggest that the existing literature
supports the existence of significant differences in serum LDH levels
among patients with preeclampsia compared to healthy controls. This
finding is more predominant in women with severe preeclampsia, compare
to those with mild features of the disease. However, at this point it
should be noted that these findings are particularly skewed and seem to
be attributed to the poor methodological quality of included studies, as
well other potential factors (described in the materials and methods),
that we could not investigate, due to the lack of substantial
differences among the included studies. Of specific importance is the
lack of available evidence in the field of the diagnostic accuracy of
this biomarker as the vast majority of studies failed to evaluate its
sensitivity and specificity. Moreover, we observed a complete lack of
data concerning the predictive accuracy of serum LDH on determining
adverse maternal and neonatal outcomes in studies enlisted in our
systematic review.
However, this does not mean that there is no data to support the
potential use of this enzyme in the field of obstetrics as there are
scarce data that evaluate its predictive accuracy in the presence of
hemolysis. Specifically, the most recent and largest in sample size
study in the field suggests that LDH levels >400 IU/L are
associated with severe maternal and neonatal complications in the
presence of hemolysis [13]. However,
a standardized cut-off value has not been established yet as there seem
to be large discrepancies among the few studies that exist in the field
[24,
25].
Several other diseases may trigger the increase of serum LDH as well,
including pregnancy-associated thrombotic thrombocytopenic purpura,
diseases of the liver etc [26]. It
remains relatively unknown whether increases are comparable, however,
current research suggests that the use of combined examinations of LDH
with other biomarkers such as liver enzymes may help establish an
accurate diagnosis [27].