Lactate dehydrogenase isoform activity mapping in patients with intra-amniotic infection.
OBJECTIVE
Five distinct lactate dehydrogenase isoenzymes have been described. We sought to illustrate the specific amniotic fluid lactate dehydrogenase isoenzyme activity profiles in women with intra-amniotic infection.


METHODS
Amniotic fluid was retrieved from 82 women who were stratified in the following groups: (1) positive amniotic fluid cultures (n = 23 women; gestational age, 26 weeks [range, 21-32 weeks]); (2) negative amniotic fluid cultures (n = 22 women; gestational age, 30 weeks [range, 16-36 weeks]); (3) second trimester control (normal genetic karyotype; n = 17 women; gestational age, 18 weeks [range, 16-22 weeks]); and (4) third trimester control (fetal lung maturity testing; n = 20 women; gestational age, 36 weeks [range, 31-38 weeks]). The optical density of each isoform was determined relative to a standard with 5 known lactate dehydrogenase isoenzyme activities. Total lactate dehydrogenase activity was measured by the clinical laboratory immediately after retrieval and by a kinetic UV spectrophotometric assay at the time of the isoelectric focusing.


RESULTS
Infection increased total lactate dehydrogenase activity: positive amniotic fluid cultures (median, 762.4 [range, 169.3-3374.8]) vs negative amniotic fluid cultures (median, 203.7 [range, 57.8-1939.3]; U/L; P < .001]). Lactate dehydrogenase isoform profiling identified significant and specific increases in lactate dehydrogenase isoforms 3, 4 (P < .01), and 5 (P < .05) in positive amniotic fluid cultures compared to the negative amniotic fluid cultures group. A selective up-regulation in lactate dehydrogenase isoform 5 was identified at term in healthy subjects.


CONCLUSIONS
Intra-amniotic infection is characterized by an increase in the activities of lactate dehydrogenase isoforms 3, 4, and 5; advancing gestational age demonstrates an up-regulation of isoform 5 only.
Magloire
Lissa K
LK
Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University, New Haven, CT 06520, USA. lissa.magloire@yale.edu
Buhimschi
Catalin S
CS
Pettker
Christian M
CM
Sfakianaki
Anna K
AK
Hamar
Benjamin D
BD
Bhandari
Vineet
V
Buhimschi
Irina A
IA
D000328:Adult; D002821:Chorioamnionitis / Q000201:enzymology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D011247:Pregnancy; D012044:Regression Analysis
D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase