Electrophoretic patterns of lactate dehydrogenase isoenzymes in 261 benignbreast cyst fluids

BACKGROUND: Some groups have described the presence of lactate dehydrogenas e [LDH) and certain isoenzymes in breast cyst fluids, but their clinical us efulness is unknown. We have studied the behavior of LDH isoenzymes in beni gn breast cysts fluids with the aim of understand their clinical meaning. SUBJECTS AND METHOD: The study group included 261 benign breast cyst fluids classified, according to the Na+/K+ ratio, as follows: type I (Na+/K+ less than or equal to 3): 188, and type II (Na+/K+ > 3): 73. The electrophoreti c LDH isoenzymes analysis was carried out with the PARAGON system and the A ppaise Junior densitometer from Beekman Instruments (U.S.A.). RESULTS: The results were as follows: a) type II was more frequently associ ated with the presence of LDH than type I breast cyst fluids (41/73 vs 9/18 8; p < 0.0001), and b) the LDH5 isoenzyme positivity was higher in type II than in type I breast cysts fluids (29/41 vs 4/188; p < 0.001) also and it correlated with higher pH, Cl-, carcinoembryonic antigen and Na+/K+ ratio v alues. CONCLUSIONS: Our results led us to consider that LDH and LDH5 isoenzyme pos itivity is associated with type II breast cyst fluids, suggesting that it d oes not reflect a higher transformation risk, but rather that is a conseque nce of cyst evolution and of its lining wall.