September is Menopause Awareness Month.


In support of Menopause Awareness Month, and women struggling with Hot Flashes everywhere, I want to highlight 5 unlikely causes of Hot Flashes.  Sure low Estrogen can cause Hot Flashes, but is that all there is to a Hot Flash?


For so many, Menopause or Peri-menopause for women means Hot Flashes.  Hot flashes are the #1 identified menopausal symptom.   Whether they be day or night, they are still Hot Flashes.  Some women struggle with severe Hot Flashes, other women battle almost no Hot Flashes.  Why the difference?  Simply stated, Hot Flashes are complex.  If Hot Flashes were simply the result of a decline in Estrogen during the Menopause transition, as most marketing implies, then all women would struggle with Hot Flashes in the Menopause transition.  But obviously, Hot Flashes (and Menopause for that matter) is so much more than declining Estrogen levels.  The following 5 unrecognized causes of Hot Flashes will reveal the complexity of the dreaded Hot Flash.



The first unrecognized cause of Hot Flashes is stress—though stress is everywhere.  I have repeatedly pointed out the CDC statistic that up to 90% of primary care doctor visits are related to stress.  Think about that—90%.  But how can stress precipitate the dreaded Hot Flash?  The Hot Flash precipitated by a stress/rushed morning is a common story.  There are several proposed mechanisms of how stress can precipitate Hot Flashes.  First, Stress and the need for an increase in Cortisol production, has been proposed to alter hormone production to cortisol away from Progesterone.  This proposed drop in Progesterone can precipitate Hot Flashes.  This has been called the “Pregnenolone Steal” as Pregnenolone is the precursor to Progesterone.  Though no studies have been published on “Pregnenolone Steal”, the term is a more descriptive term regarding the chronic effects of stress on adrenal Hormone production, which has been well described.  The second proposed mechanism is due to the suppression of sex hormones (Estrogen, Progesterone, and Testosterone) due to the elevated Cortisol production in stress.  Think about it, if you are running from a tiger (stress response), is your body really interested in procreating at that point?  It shouldn’t, because if it does then you will become dinner.  However, the most likely direct culprit of Stress induced Hot Flashes are the catecholamines.  The specific implicated catecholamines are epinephrine and/or norepinephrine.  You may know them as adrenaline and noradrenaline.  They are responsible for the immediate stress response.  The likely mechanism of action is an increase in heart rate, increased vascular dilation (vasodilation), and a lowering of the thermoregulatory set point in the hypothalamus that results in heat loss and thus sweating—affectionately known as a Hot Flash.  When heat builds up, it has to be released.


The second unrecognized cause of Hot Flashes is low Progesterone levels.  Progesterone is the per viable red-headed step child when it comes to a Hot Flash.  Though Progesterone had its coming out party many years ago with John Lee, its contribution to Hot Flashes has somehow missed the spotlight.  This is evident in Hormone Replacement Therapy (HRT) in a women immediately following a hysterectomy.   Estrogen therapy for women post-hysterectomy will begin even before the anesthesia wears off in the recovery room.  Yet, prior to the hysterectomy, the offending organ (the uterus), needed Estrogen and Progesterone to produce a normal cycle.  The actual first hormonal change that a women will see in perimenopause is a decline in Progesterone.  Contrary to marketing-based medicine, an Estrogen decline is not the precipitating hormone change in the menopause transition—that is Progesterone.  The decline in Progesterone is due to a less than optimal ovulation.  When a women is born, she is born with all the eggs she will ever have during her lifetime.  The old adage is “leave the best for last”.  At least when it comes to ovulation, the best go first, and the worst are left for last.  These less than optimal eggs, when released during ovulation, result in an equally less than optimal corpus luteum and it is the corpus luteum that is responsible for Progesterone production.  Follow the timeline?  Older eggs leads to poor ovulation, which leads to poor corpus luteum function, which results in low Progesterone production.  The likely mechanism of the Hot Flash is hormonal imbalance.  The addition of Progesterone alone has been shown to resolve 83% of Hot Flashes.  Another proposed mechanism of low Progesterone and Hot Flash generation is inflammation.  A low Progesterone level allows for an increase in inflammation.  This relationship is seen in women with infertility and luteal phase defects.  This condition occurs when the previous mentioned dysfunctional corpus luteum produces sub-optimal Progesterone in a cycling women.  This luteal phase defect of Progesterone production can lead to irregular cycles and infertility.  The result is an increase in Tumor Necrosis Factor alpha (TNF-alpha).  The opposite applies as well—Progesterone reduces TNF-alpha and other inflammatory signals.  TNF-alpha is an inflammatory cytokine.  Think of it as a means of communication between the different parts of the immune system.  This increase in inflammation results in an increase in heat (one of the cardinal symptoms of inflammation), vascular dilation and the heat has to go some where—thus a Hot Flash.


The third unrecognized cause of Hot Flashes is an elevated Estrogen; or as described by John Lee–Estrogen dominance.  In the previous paragraph I briefly discussed hormone imbalance.  The same applies here.  Just as a Progesterone deficiency precipitates an imbalance, excess Estrogen precipitates an imbalance.  The means to the excess Estrogen or Estrogen dominance is different though.  Excess Estrogen can result from endogenous production.  That is Estrogen production above and beyond that needed for a normal, functional cycle.  This usually is the result of peripheral production from fat via aromatase activity.  The second means to excess Estrogen is exogenous Estrogen.  This exogenous Estrogen is primarily the result Hormone Replacement Therapy (HRT) or Bioidentical Hormone Replacement Therapy (BHRT).  According to marketing-based medicine, Hot Flashes are the result of an Estrogen deficiency.  However, if the cause is due to a decline in Progesterone (as described above) during perimenopause, then any extra Estrogen added will widen the imbalance between Estrogen and Progesterone that already existed to begin with.  The third means to excess Estrogen is the previously mentioned drop in Progesterone.  A normal Estrogen level with a decline in Progesterone creates an effective excess Estrogen imbalance not due to excess Estrogen, but due to the low Progesterone.  In fact, a decline in Progesterone results in a loss of regulatory control of Estrogen and an actual increase in Estrogen–not due to an increase in Estrogen production, but due to a decrease in Progesterone.


The fourth unrecognized cause of Hot Flashes is diet.  Everything starts with diet and Hot Flashes are no different.  The word Hot Flash has only recently entered the language of many Asian cultures due to its historical absence.  Why its absence?  The absence of simple sugars in the traditional Asian diet.  High simple sugar intake can precipitate Hot Flashes.  This occurs through the ups and downs of insulin.  A high sugar load will cause a rapid insulin release.  What goes up, must come down and that applies to Insulin as well.  The equally rapid fall in insulin can precipitate “hypoglycemia” that leads to Stress (see Cortisol and catecholamines above) and thus a Hot Flash.  More than just the type of food i.e. high sugar/carbs, but also the food itself can precipitate Hot Flashes.  Most are aware of increasing gluten sensitivity in the American population.  This is an inflammatory response to gluten, which is different from Celiac disease.  This can be localized to the gut or it can be systemic.  Other foods can precipitate similar inflammatory responses.  Soy, eggs, and dairy, with gluten, are the 4 most common food sensitivities out there.  These foods, and others, precipitate inflammation that produces Hot Flashes as described above—vascular dilation, heat production and the heat has to go somewhere and thus a Hot Flash.  Other foods, such as caffeine, spices, and alcohol are commonly associated with Hot Flashes.


The fifth unrecognized cause of Hot Flashes is Thyroid dysfunction.  This can include both over active and under active thyroid conditions.  The over active thyroid, Hyperthyroidism, is a more direct, immediate effect.  Hyperthyroidism itself will elevate the core temperature.  This increase in core temperature has to be release somehow—Hot Flash.  If a women has a low threshold for Hot Flashes, other hormone imbalances, then the threshold to the generation of a Hot Flash is lowered and precipitated quit easily.  This Hot Flash precipitation is common in women on HRT or BHRT receiving supra-physiologic dosing of Thyroid hormone.  The link between Hypothyroidism is a little more indirect.  One of the more common forms of Hypothyroidism is an autoimmune disease cause Hashimoto’s disease.  This is inflammation directed against itself—auto-inflammation.  Remember, inflammation will increase heat production and vasodilation.  More indirect than that, Hypothyroidism will slow the metabolic rate.  A slow metabolic rate means weight gain.  Excess fat around the belly equals increased inflammation.  Fat cells are not inert (recall previously mentioned production of Estrogen).  Fat cells are very biologically active and one of their often disrupting functions is the production of inflammatory signaling—inflammation.  And remember, heat is one of the cardinal symptoms of inflammation.


Are Hot Flashes caused by low Estrogen in women?  Of course they can be, but I hope I have been able to expand the scope and complexity of the problem when it comes to the causes of Hot Flashes in women.  May September be a cool, Hot Flash free month.


By the way, men are not immune to Hot Flashes either.