When evaluating a patient whose primary complaint is amenorrhea, the nurse must be aware that amenorrhea is most often the result of

A. Eating disorders can cause amenorrhea due to low body fat and hormonal imbalance, but they are less common causes compared to pregnancy. The hypothalamic-pituitary-ovarian axis is suppressed in severe nutritional deficiency. B. Stress can lead to temporary amenorrhea through hypothalamic suppression and disruption of gonadotropin-releasing hormone, but it is not the most frequent cause in reproductive-age women. C. Pregnancy is the most common and primary cause of secondary amenorrhea because elevated human chorionic gonadotropin (hCG) levels suppress ovulation and menstruation. A pregnancy test is always the first diagnostic step. D. Excessive exercise can result in amenorrhea due to decreased energy availability and altered gonadotropin levels, but it accounts for fewer cases compared to pregnancy in the general population.