Electrolytes and trace elements in human breast cyst fluid.

Gross cystic breast disease (GCBD) is one of the most common breast diseases, and women with apocrine (type I) cysts are at higher risk of developing breast cancer than women with flattened (type II) cysts. Type I cysts contain fluid with an electrolyte composition similar to that of intracellular fluid (Na/K ratio <3), whereas type II cysts fluid's content resembles that of plasma (Na/K ratio >3). The electrolyte composition of breast cyst fluid (BCF) has been investigated intensively; however, there have been only a few studies in literature reporting the content of trace elements in BCF. The aim of this study was to compare the concentrations of Na, K, Ca, P, Zn, Cu, Fe, and Na/K and trace element ratios in breast cyst fluid in two subgroups of breast cysts. Sixty-three BCF were obtained by needle aspiration from premenopausal women with GCBD diagnosed by clinical, xheromammographic, and cytological studies. After separation of cells for cytological evaluation, the cyst fluid was centrifuged and supernatant stored at -80 degrees C until the analysis. Sodium, potassium, calcium, phosphorus, and iron were measured using Roche Diagnostics commercial kits on Hitachi 747-200 autoanalyzer. Measurements of copper and zinc were performed by flame atomic absorption spectrophotometer on Shimadzu AAS 680. We found statistically significant higher K, lower Na, higher phosphorus concentrations, and lower Na/K ratios in type I cysts when compared with type II cysts' values. Median values of Na/K ratio in type I and in type II were 0.32 and 6.2, respectively. Higher Zn, Cu, and Fe concentrations with respect to median values were noted in type I cysts; higher [Na.Cu/K.Zn], [Na.Cu/K.Fe], and [Na.Zn/K.Fe] ratios were found in type II cysts. A significant negative correlation existed between Na/K and Cu, and a significant positive correlation between Na/K and Fe in type II cysts (r = -0.660, p = 0.007; r = 0.615, p = 0.014, respectively). We can conclude that the trace elements content of BCF, in addition to electrolytes, could be useful in classifying the breast cyst. Future studies in larger series are needed to confirm these data.