Isoenzymes of lactate dehydrogenase in amnionic fluid in early pregnancy.

Electrophoretic fractionation of lactate dehydrogenase in amnionic fluid was utilized to demonstrate the five isoenzymes usually found in a variety of human tissues. The anaerobic portion of the isoenzyme spectrum was prominent, and the percentage distribution may be related to the metabolic activities of tissues contributing to the formation of the fluid. In contrast to the placenta, an "extra" isoenzyme was not found in the fluid.