A 14-year-old girl is brought to the office due to abnormal menstrual periods. Since menarche, the patient's menses have been unpredictable. She does not have menstrual bleeding each month, and when she does have a menstrual period, she bleeds for 7-10 days and occasionally needs to use nearly twice as many tampons a day as her older sister. The patient underwent menarche a year ago, and her last menstrual period was 6 weeks ago. Medical history is unremarkable. BMI is 22 kg/m². Urine pregnancy test is negative, and a complete blood count is normal. Which of the following is the most likely cause of this patient's irregular bleeding?

Question

Quizplus · Accepted Answer

11ec160b_3cbc_ccb9_9249_bdb2980570c9_MD0001_00 In most adult women, menstrual cycles consistently last 21-35 days, with menses lasting between 4 and 6 days. In a normal ovulatory cycle, the LH surge triggers oocyte release, and the dominant follicle luteinizes into a corpus luteum, which secretes progesterone. Progesterone is needed to convert the endometrium from the proliferative phase to the secretory phase, which stabilizes the endometrium and prepares it for implantation. If fertilization and implantation do not occur, the corpus luteum degenerates, and the loss of progesterone causes the endometrium to degenerate, resulting in menstrual bleeding. Adolescent girls typically have an immature hypothalamic-pituitary-ovarian axis for several years following menarche because the hypothalamus' pulsatile release of GnRH is low and irregular. This results in decreased gonadotropin (FSH, LH) levels with an inability to mount an LH surge (Choices A and D), leading to anovulation and cycles without progesterone secretion. Without progesterone, the endometrium remains in the proliferative phase and can become disorganized and fragile with unstable vasculature, resulting in longer menstrual cycles with irregular bleeding and intermittent spotting (Choice B). (Choice C) Excessive peripheral estrogen production is seen in women with obesity due to the conversion of androgens to estrogens in peripheral tissue. This can result in irregular menstrual bleeding (from disorganized and unstable proliferative endometrium), but is unlikely in this patient with a normal BMI. Educational objective: Intermittent anovulatory cycles are common in the first few years after menarche due to an immature hypothalamic-pituitary-ovarian axis producing low and irregular GnRH pulses. As a result, adolescent girls may have menstrual cycle variability with intermenstrual spotting and heavier menstrual bleeding. __________ References: Clinical review: adolescent anovulation: maturational mechanisms and implications. (http://www.ncbi.nlm.nih.gov/pubmed/23913942)

A 14-Year-Old Girl Is Brought to the Office Due to Abnormal