Variability of serum CA 125 levels in healthy women as a function of age, hormonal status, and other conditions

Knowledge of the factors influencing serum concentrations of CA 125 have led the validity of a single cut-off value to be questioned. The aims of the present study were to evaluate CA 125 levels according to age, menopause, body mass index (BMI), smoking, parity, variability during the menstrual cycle, biological variation, index of individuality (II), and critical difference (CD). Sixty-five healthy women distributed in 2 groups, non-menopausal and menopausal, were included. The main results of the study demonstrate that there is a clear relationship between CA 125 levels and age: serum levels of CA 125 were significantly lower in menopausal women than in non-menopausal women, with 95th percentiles of 30.52 U/ml and 18.30 U/ml, respectively. No variations were found during the menstrual cycle, although a CA 125 value higher than the conventional cut-off value was observed during the follicular phase. In non-menopausal women, intra-and interindividual biological variations were 14.23% and 43.57%, while in menopausal women interindividual biological variation was 36.25%. CD was 42.73% and II was 0.11. No significant differences were found between smokers and nonsmokers or according to parity. No relationship was found between CA 125 levels and BMI. In conclusion, knowledge of the factors influencing serum concentrations of CA 125 according to different physiologic and clinical factors and careful adjustment of cut-off values could improve interpretation and identification of subgroups at risk for ovarian carcinoma.