When comparing pairwise subgroups with BC, fibroadenomas, and healthy controls before/after menopause, it was shown that in each pair there were statistically significant differences in the concentrations of albumin (p = 0.0486, p < 0.0001 and p = 0.0001 for BC, fibroadenomas, and healthy controls, respectively), imidazole compounds (p = 0.0005, p = 0.0001 and p = 0.0221), and catalase activity (p = 0.0263, p = 0.0159 and p = 0.0009), as well as pH (p = 0.0007, p = 0.0053 and p = 0.0001), which allows us to associate these biochemical parameters with menopause status. The gene discussed is CAT; the disease is breast cancer.