There are dramatic changes in hormone patterns that occur well before the cessation of menses. The initial clinical manifestation of an alteration in the axis is shortening of the menstrual cycle, primarily a shortening of the follicular phase, often beginning as women approach their early 30s. Later in the 40s there are skipped ovulations often leading to a lengthening of the cycle.

As the number of follicles declines, there is a corresponding decrease in serum inhibin B and antimullerian hormone (AMH) levels. The reduction of inhibin B (and its negative feedback on pituitary FSH) leads to a corresponding increase in serum FSH. These higher levels of FSH stimulation often result in higher than normal levels of estradiol in the follicular phase of the cycle. Clinically, these changes may present in women with shorter but heavier menstrual cycles. Aromatase activity increases with age and increased body fat and can also contribute to higher estrogen exposure. In the late menopausal transition, there is increased cycle irregularity and marked variations in serum FSH and estradiol levels. These changes may be compounded by a decreased hypothalamic-pituitary sensitivity to estradiol.

After menopause, ovarian production of estradiol falls dramatically, often reaching its nadir around age 55. The postmenopausal ovarian androgen production falls by about 50% and remains stimulated by high levels of LH. Estrone is now the predominant circulating estrogen and is primarily produced by extraglandular conversion of circulating androstenedione. After menopause, about 85% of androstenedione comes from adrenal secretion and about 15% from the ovaries. The conversion of androstenedione to estrone takes place mainly in adipose tissue; therefore, obese women have higher levels of estrone and are less likely to be as estrogen deficient as their slender counterparts.

While menopause is the most common diagnosis in women between 40 and 55 years who present with amenorrhea and concomitant flushes and sweats, it is prudent to consider other etiologies if indicated. Pregnancy should always remain in the differential in any woman, even during the menopausal transition, due to the irregular ovulation that may still take place. Hyperthyroidism may mimic symptoms of menopause. Clinical presentation can guide whether TSH, a screening test, is needed.

Rare diagnoses that may be confused with menopausal symptoms include tumors or medications. Carcinoid, pheochromocytoma or other malignancies should be considered if atypical symptoms or physical findings are present. A thorough medication history is always indicated.

Since estrogen plays such a widespread and important role in many tissues in the body, its decline can be manifested in a varied and extensive fashion.

Hot flushes

Hot flushes represent the pathognomonic symptom of menopause. They occur in up to 75% of postmenopausal women. Time of onset varies as they can begin during either the perimenopausal or menopausal years. The majority of women experience spontaneous resolution of hot flushes within a few years after menopause but they can persist for more than 5 years. Typical symptoms of hot flushes include an acute sensation of heat that starts in the face and upper chest and then becomes generalized, perspiration, and palpitations. These sensations last approximately 2–5 minutes, after which time chills or shivering may occur. Flushes can occur during the day and night and can be in groups or appear as single episodes.

A definite pathophysiologic explanation for hot flushes is still unknown, but they are attributed to estrogen withdrawal at the hypothalamus. This deficiency causes thermoregulatory disruption due to inappropriate peripheral vasodilation, leading to heat loss and a decrease in the core body temperature. Readjustment of core temperature to normal occurs with shivering. Sleep disturbance represents an important consequence of hot flushes. In many women these sleep disturbances lead to chronic insomnia and have a significant negative impact on quality of life issues.

Treatment options include reducing room temperatures, wearing layered clothing and avoiding hot foods. The most effective and low-cost treatment for moderate-to-severe hot flushes is hormone therapy. Low-dose conjugated estrogen and 17β-estradiol (oral or transdermal) are both effective, especially if given continuously. A re-evaluation of symptoms may be performed 6 weeks to 3 months after initiation of therapy but can be prolonged up to 1 year after adequate counseling. A yearly discussion on the risks and benefits of hormone therapy, reassessment of symptoms, and review of therapy options is important. When therapy is discontinued, it is best to taper the patient off the medications slowly (discontinue one pill per week or decrease the amount of estrogen in transdermal patches weekly).

Hormone therapy may not be a treatment option due to contraindications, side effects or patient preference. In this case, there are alternative treatments that may be effective. Selective serotonin reuptake inhibitors (SSRIs) and selective norepinephrine reuptake inhibitors (SNRIs) are generally the first alternative treatment option. These medicines are well tested and generally well tolerated but they should be avoided in patients on tamoxifen as adjuvant therapy for breast cancer, since SSRIs decrease its antiestrogenic activity and therefore may affect prognosis. Gabapentin is another agent employed in treatment. The ideal time of administration is at night, since it may cause drowsiness. Clonidine is a less effective option, but may be considered especially in women with hypertension.

Complementary treatments are growing in popularity and include soy, other phytoestrogens, black cohosh, vitamin E, and acupuncture. Many of the studies have mixed outcomes for the treatment of hot flushes. Furthermore, soy and black cohosh may have estrogenic effects on the breast.

Genitourinary atrophy

Vulvar, clitoral, and vaginal atrophy are changes seen after estrogen depletion. The initial alterations in the epithelium manifest as fewer superficial cells, more parabasal cells, with decreased support and elasticity of the tissue. The vaginal pH becomes more basic, thereby providing a more conducive environment for vaginal infections via growth of different types of bacteria. After long-term estrogen deficiency, there is atrophy of the vessels, muscles, and stroma of the vagina. This results in less blood flow to the area and more advanced signs of atrophy, such as a decrease in vaginal length and constriction of the vagina. Atrophic vaginitis can cause itching, burning, discomfort, dyspareunia, and also vaginal bleeding when the epithelium thins.

The trigone of the bladder and urethra are embryologically derived from estrogen-dependent tissue, and estrogen deficiency can lead to their atrophy, producing symptoms of urinary urgency and incontinence, dysuria, and urinary frequency. Another problem that can develop with decreased circulating estrogen levels is decreased synthesis of collagen that forms the connective tissue beneath the vaginal epithelium. These atrophic changes may decrease the support of the posterior urethrovesical angle and urinary stress incontinence can develop. Mild symptoms of vaginal dryness may be managed through the use of vaginal lubricants. However, more symptomatic patients find the most relief with either systemic or vaginal estrogen therapy. The advantages of vaginal estrogen administration are that it often works very quickly and the low systemic levels associated with its use have very low if any impact on coagulation factors, breast tissue, and endometrium. The advantages of systemic estrogen therapy often include ease in use, a lack of the messiness of vaginal products, and its concomitant beneficial effect on hot flushes and osteoporosis.

While estrogen relieves the symptoms of atrophic vaginitis, there are conflicting results in its treatment of urinary incontinence. While a meta-analysis did report subjective improvement in incontinence, the Women’s Health Initiative (WHI) demonstrated a worsening of incontinence in older women on both estrogen alone and combination estrogen and progestin.

Osteoporosis

Osteoporosis is defined as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fractures. Osteoporosis is a silent disease that is usually asymptomatic until fractures occur. Early diagnosis and treatment are essential to avoid fractures of the skeleton. Postmenopausal osteoporosis initially affects trabecular bone, which is present in the vertebral column and distal radius. Osteoporosis develops more slowly in cortical bone, which is present in the hip and limb bones. Bone mass is increased in black, obese, and athletic women and is decreased in frail, light-skinned, sedentary women. Without antiresorptive treatment, women often lose about 1–1.4% of bone mass each year after menopause. In women undergoing a normal menopause, fractures begin to occur at about age 60 in structures composed mainly of trabecular bone, such as the vertebral spine and distal portion of the radius. By age 60, 25% of white and Asian women have spinal compression fractures. Loss of bone mass in cortical bone occurs at a much slower rate, so osteoporotic fractures of the femur usually do not begin to occur until about age 70 or 75.

Since osteoporosis is asymptomatic, its presence needs to be detected by imaging studies. At least 25% of the bone is lost before osteoporosis is diagnosed by routine x-ray examination. Dual-energy x-ray absorptiometry (DEXA) is the best way to measure bone mineral density in the sites at which fractures are most likely to occur – the spinal column and hip. The National Osteoporosis Foundation has stated that bone mineral density measurements are indicated when clinical decisions will be influenced by the information gained. Indications for measuring bone mineral density in postmenopausal white women include:

• all postmenopausal women under age 65 with at least one risk factor for osteoporosis
  
• all women 65 or older
  
• postmenopausal women with fractures
  
• women taking postmenopausal estrogen for prolonged periods of time

A careful history and physical examination will determine whether risk factors for the development of osteoporosis are present. Factors known to increase the risk of osteoporosis include: