to the editor: In the article “Diagnosing Night Sweats,”¹ the authors overlooked the most prevalent and easy-to-diagnose type of night sweats: those occurring in women during perimenopause. Persons most likely to ask their family physician about night sweats are women in their late 30s to early 60s who are in the menopausal transition or the early years of menopause. This group of women is not even mentioned in the abstract of the article.¹ When menopausal women are mentioned on the third page of the article,¹ the description is inappropriately brief and somewhat inaccurate. Table 1 of the article¹ should be revised to list perimenopausal women instead of “ovarian failure.” It also should include the “selective estrogen receptor modulator” drugs, such as tamoxifen and raloxifene.

Although hot flushes and night sweats (vasomotor symptoms) often are considered to be typical of menopause, there are good epidemiologic studies showing that many women experience them before they cease menstruation for a year and become menopausal. One study² found that approximately 25 percent of menstruating women in midlife reported vasomotor symptoms before they had skipped one or several periods. Subsequent population-based studies³ suggest that vasomotor symptoms, including night sweats, are common during perimenopause. Vasomotor symptoms commonly begin at night and have a characteristic pattern in regularly menstruating women in their late 30s through 40s who are beginning the process of ovarian aging. Vasomotor symptoms are typically cyclic, maximal before menstrual flow,⁴ and more common in blacks than in white urban women with regular menstrual cycles.⁵

The use of “ovarian failure” in Table 1¹ is anachronistic and inappropriately offensive in use of language. It also misrepresents the time course of hot flushes/night sweats in a woman’s reproductive life cycle because the majority of women who have night sweats associated with menopause begin experiencing them when their cycles are still regular or becoming irregular. At this stage, follicle-stimulating hormone is highly variable and not diagnostic.⁶

In summary, whenever a woman reports night sweats, the attending physician must ask about other changes in her menstrual patterns and cyclic experiences. If she has experienced such changes, and also reports that her hands are warm during night sweats or hot f lushes, these changes are more likely vasomotor symptoms and less likely evidence of a disease process such as pheochromocytoma that is associated with peripheral vasoconstriction. It is inappropriately worrisome for women and costly for the health care system to do extensive investigations looking for malignancy or occult infection when the occurrence of night sweats in midlife women is so common and so characteristic.

It is appropriate here to repeat the caution often taught in medical school: When hearing hoof beats, don’t look for zebras!

in reply: We thank Drs. Prior and Hitchcock for their reminder not to overlook or ignore obvious diagnoses in the pursuit of rare or esoteric ones. Our interest in night sweats was in determining which “zebras” might be considered when no “hoof beats” were heard. As such, our article¹ was meant to aid the physician who was evaluating a patient complaining of night sweats without an obvious cause. We agree that the gradual decline in ovarian function seen in women in their perimenopausal years can lead to hot flushes that may manifest as night sweats. We regret leaving the specific term “perimenopause” out of Table 1 in our article.¹ Obviously, the term “ovarian failure” was not meant to be offensive. It merely implies that the ovaries have ceased functioning properly, analogous to the way the terms “heart failure,” “kidney failure,” or “liver failure” are used. Such terms do not necessarily imply complete cessation of function, but rather a gradual decline or worsening in function. Again, we appreciate this feedback and the additional useful information provided by Drs. Prior and Hitchcock.