The concentration of testosterone in cyst fluid and serum was significantly correlated (r = 0.68; p = 0.0057; n = 15), whereas the concentrations of IGF-1, insulin, erythropoietin, growth hormone, estradiol, and triiodothyronine in cyst fluid and serum were not significantly correlated (correlation coefficients 0.03–0.42; n = 15). Here, EPO is linked to cyst.