Hot Flushes

Hot flushes are due to vasomotor instability and are usually related to the female climacteric. The aetiology of hot flushes would seem to be related to very high levels of gonadotrophins as the ovaries fail but there is still much that is not understood about their aetiology. They do not tend to occur in men as there is not a similar rapid decline in hormones. When hormone levels do fall in elderly men it is not accompanied by a surge in gonadotrophins. However treatment for prostate cancer that involves suppression of testosterone production can produce a picture similar to menopausal hot flushes in women and can be just as severe.

• About 75% of women experience hot flushes during the perimenopause, beginning on average 2 years before the cessation of menses.
• 85% of these women continue to experience hot flushes for more than 1 year and up to 50% for as long as 5 years.
• They are common also in men on androgen deprivation treatment.

Risk factors

• They tend to be more severe in women of low body weight, those who take little or no exercise and those who smoke cigarettes.
• They seem to be more common in black women and less common in Chinese women.
• An abrupt or early menopause causes more severe symptoms. Thus surgical oophorectomy or its equivalent induced with chemotherapy, radiation or drugs produces more pronounced symptoms than a natural menopause.

• Hot flushes may last between a few seconds and 10 minutes but an average is around 4 minutes. Frequency may be from every hour to a couple of times a week.
• There is a sensation of intense heat and a feeling that the face and whole body is flushing. It is often difficult to ignore and women having hot flushes often fling open windows when all around them are anything but warm. Flushing and sweating may not be apparent to the observer but the sufferer tends to be very self-conscious of the affliction.
• Lack of concentration and poor memory are common.
• Sleep disturbance is common with night sweats. Features of depression are not unusual.
• Frequent flushes and disturbance of sleep may well be a major contributor to the commonly observed adverse effect on mood. There is evidence that the sex hormones do have an effect on mood and wellbeing in both men and women. Hormone replacement improves fatigue, depression, headaches and libido in men as well as women.
• The flushing is often quite visible and accompanied by sweating. Inappropriate vasodilatation leads to a slight drop in core temperature. Between attacks there is no abnormality to be found.

• There may be a history of menstruation becoming irregular or ceasing but not necessarily. There may have been surgery, radiotherapy or chemotherapy involving removal or inactivation of the ovaries. Similar causes of sudden withdrawal of sex hormones in men produce a similar response.
• If there is doubt about the diagnosis then oestrogen levels (or testosterone in men) will be low and FSH and LH will be raised (it may be necessary to obtain more than one blood sample to confirm the elevated gonadotrophins).
• The following list includes other causes of flushing to consider:
  • Carcinoid tumours
  • Medullary carcinoma of thyroid
  • Carcinoma of pancreas
  • Phaeochromocytoma (may be part of a multiple endocrine neoplasia syndrome)
  • Brain tumours and spinal cord lesions (can lead to vasomotor instability)
  • Frey's syndrome (flushing when the affected person eats, sees, thinks about or talks about certain kinds of food which produce strong salivation; may occur as a complication of parotid gland surgery)
  • Some food substances, e.g. monosodium glutamate
  • Some drugs, e.g. nitrates, nicotinic acid and calcium channel blockers, anti-oestrogens (including tamoxifen), SERMs (selective oestrogen receptor modulators) e.g. raloxifene, anti-androgens (e.g. cyproterone), danazol and goserelin (tolbutamide and chlorpropramide are the best known, but rarely prescribed nowadays)

• Hot flushes do not threaten life but they can have a marked effect on the quality of life. They will subside with time but a sympathetic and positive approach is required.
• Trials of treatment for hot flushes may have to be interpreted with caution as the placebo response can be as high as 20 to 30%.¹ Almost all trials are on women as symptoms are much more common in women than men. Where both men and women have been included in trials the results seem similar and so extrapolation appears valid.
• Despite the very high placebo response the benefits of behavioural modification are very limited and most trials have small numbers.² Diet and exercise has also shown very little effect in some studies.³ However the following advice should be given:⁴
  • Take regular exercise, wear lighter clothing, sleep in a cooler room, and reduce stress.
  • Avoid possible triggers, such as spicy foods, caffeine, smoking, and alcohol.
• The most effective form of treatment is hormone replacement therapy but concern over long term safety has reduced its popularity with both doctors and patients.⁵ HRT has to be tailed off to prevent recurrence of the problem. The necessary duration of treatment is very variable but it may have to be for months rather than years.
• Alternative treatments to HRT include:⁴
  • The SSRI antidepressants seem to be effective,⁶ e.g. paroxetine (20 mg daily), fluoxetine (20 mg daily), citalopram (20 mg daily), or venlafaxine 37.5 mg twice a day (unlicensed).
  • Clonidine 50 to 75 micrograms twice a day (licensed use).
  • A progestogen, e.g. norethisterone or megestrol (both unlicensed).
  • The anticonvulsant gabapentin is also effective.⁶
• Phytoestrogens, usually derived from soya or red clover, are at best just moderately effective.⁷ Many other herbal remedies have been used but vigorous trials tend to show little or no benefit.⁸
• Vitamin E at 800 IU daily is quite popular but the proven benefit is not great.⁹
• As a non-hormonal treatment, beta blockers were once popular but have been shown to be ineffective.¹⁰ Clonidine in low dose probably does work but side effects can be a problem.⁶
• Bandolier concluded that acupuncture does not work.¹¹