Hot flashes are among the most prevalent symptoms of menopause. They occur in about 75 percent of naturally postmenopausal women and in more than 90 percent of women who have undergone hysterectomy. But a new study finds many women leave the condition untreated, which leads to extra outpatient visits and costs.

"The untreated women had more than a million and a half visits to the doctor and incurred $370 million in expenses, in terms of medical costs and work lost," said Dr. Holly Thacker, who did not take part in the study but treats menopausal women at Cleveland Clinic.

Yale University researchers used health insurance claims to compare more than 250,000 menopausal women experiencing hot flashes with more than 250,000 women without. Over the course of a year, they found the women with untreated hot flashes scheduling more than a million extra outpatient visits, which resulted in a cost of almost $370 million because of medical bills and lost work.

Researchers say it may be related to the fact that women experiencing hot flashes typically experience other signs and symptoms of menopause at the same time. They include: disturbed sleep, depression, irritability and difficulty concentrating.

Researchers contend many women forgo the use of hormone therapy and elect to navigate work, while experiencing untreated or inadequately treated hot flashes. They suggest doctors discuss hot flashes and their effects on daily function at each annual physical.

"Many of the symptoms that a lot of mid-life women have: whether its fatigue, or foggy thinking, joint pain, is related to the lack of estrogen," explained Thacker. "And a lot of times women and even their doctors don't realize that, so if you're in the midlife range and you're having some symptoms, you're having trouble with work productivity ask if this is related to menopause."

The study was funded by Noven Pharmaceuticals. The findings were published in the online issue of the journal Menopause.