A 39-year-old woman, gravida 1 para 1, comes to the office with abnormal uterine bleeding. The patient underwent menarche at age 15 and had irregular menses that normalized with oral contraceptives. She used oral contraceptives until 4 years ago, when she became pregnant and had a cesarean delivery with tubal ligation. The patient's menstrual cycles after delivery occurred monthly with 4-5 days of moderate bleeding. However, over the last year, her menses have become increasingly irregular and now occur every 2-3 months, with heavier bleeding and passage of clots. She also has had difficulty concentrating at work due to increasing irritability and depressed mood. She has no headaches or hot flushes. Vital signs are normal. BMI is 26 kg/m². Skin is cool and dry. Pelvic examination reveals a well-rugated vagina, mobile uterus, and small, nontender ovaries. The remainder of the physical examination is normal. Pregnancy test is negative. This patient's laboratory results would most likely reveal which of the following?

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11ec25c8_d3c7_3f99_bc81_19d274dd4794_MD0003_00 This patient has hypothyroidism, a common endocrine disorder that causes abnormal uterine bleeding due to disruption of the hypothalamic-pituitary-ovarian axis. Patients with hypothyroidism also have cool, dry skin and metabolic slowing, which often leads to cognitive (eg, difficulty concentrating) and psychiatric (eg, depression, increased irritability) effects. In patients with hypothyroidism, low thyroxine levels feed back to the hypothalamus and increase the secretion of thyrotropin-releasing hormone, stimulating the anterior pituitary and increasing TSH and prolactin levels. The resulting hyperprolactinemia inhibits the hypothalamus and anterior pituitary, causing decreased FSH and LH levels. The decreased, nonpulsatile FSH and LH levels result in anovulation and abnormal uterine bleeding (eg, oligomenorrhea), as seen in this patient. Treatment with thyroxine hormone replacement achieves symptom resolution (eg, regulation of menses) and normalizes TSH and prolactin levels. (Choice A) Patients undergoing menopause have an elevated FSH level due to age-related ovarian follicle depletion but normal TSH and prolactin levels. The median age of menopause is 51 and patients typically have hot flushes and vaginal atrophy (eg, loss of rugation), making this diagnosis unlikely in this patient. (Choice B) Patients with functional hypothalamic amenorrhea have secondary amenorrhea due to low FSH levels but normal TSH and prolactin levels. This type of amenorrhea typically occurs due to stress and a relative caloric deficiency (eg, overexercising, undereating). Patients with this condition are usually underweight (ie, BMI <18.5 kg/m²) and have signs of estrogen deficiency (eg, vaginal atrophy). ² (Choice C) Elevated prolactin levels from prolactinomas cause low FSH levels, which result in anovulation and abnormal uterine bleeding despite normal TSH levels. Prolactinomas do not typically cause depressed mood, irritability, or skin changes. (Choice D) Polycystic ovary syndrome causes abnormal uterine bleeding due to hyperandrogenism (eg, acne, hirsutism); FSH, TSH, and prolactin levels are typically normal. These patients have oligomenorrhea due to chronic anovulation from enlarged, polycystic ovaries. This patient's ovaries are small and nontender. Educational objective: Hypothyroidism disrupts the hypothalamic-pituitary-ovarian axis. Low circulating thyroxine levels increase the excretion of hypothalamic thyrotropin-releasing hormone, which in turn stimulates anterior pituitary production of both TSH and prolactin. The resulting hyperprolactinemia suppresses ovulation, leading to abnormal uterine bleeding (eg, oligomenorrhea). References: Hypothyroidism. (http://www.ncbi.nlm.nih.gov/pubmed/30137821) Hyperthyroidism and hyperprolactinemia: is there any association? (http://www.ncbi.nlm.nih.gov/pubmed/27540882) Hypothyroidism and its effect on menstrual pattern and fertility. (http://www.ncbi.nlm.nih.gov/pubmed/26620017)

A 39-Year-Old Woman, Gravida 1 Para 1, Comes to the Office