This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and Reproduction, Subject name: Physiology
A clinical sign indicating the onset of the menopause is: 
Select and explain. 
A. The onset of menses near age 50, B. An increase in plasma FSH levels, C. An excessive presence of corpora lutea, D. An increased number of cornified cells in the vagina
B: An increase in plasma FSH levels
Answer: B: An increase in plasma FSH levels 
Explanation: Ans. B. An increase in plasma FSH levelsOne of the first clinical measures for menopause is an increase in the serum concentration of FSH (and LH), indicative of the lack of ovarian function. Menses starts at age 12, not age 50, and its onset at this time would not indicate menopause. Excessive corpora lutea would likely indicate multiple ovulations or a failure of luteal regression. Increased vaginal cornification is an indicator of estrogen secretion, which does not occur in menopause. Menstrual cycles become irregular at menopause.