Asthma Subgroups: Premenopausal Asthma
What are some statistics?
Studies show that boys are more likely to have asthma than girls, although women are more likely to have it than men. A whopping 60% of adult asthmatics are females, of whom are 35% more likely to be hospitalized for asthma, and 40% more likely to die of asthma, compared to adult male asthmatics.1, 2
This data inspired researchers to look into it and see if they could learn why adult females are more likely to have asthma than women. What they ended up learning was that there was an entirely new asthma subgroup that was being overlooked. This asthma subgroup is now defined as Premenopausal Asthma. Data shows that up to 40% of women have this.1
So, what is premenopausal asthma?
The definition may vary from one source to another, although, for the sake of simplicity, we will define it as asthma that begins after the age of 12, or when puberty begins, and before menopause. Asthma episodes tend to to occur, or to become worse, in the first 2-3 days of the menstrual cycle, or the first few days of a menstrual period.3
It may be combined with other asthma subgroups.
Allergic Asthma. Some studies show that it is often associated with allergies. In these cases, the type of airway inflammation present would be eosinophilic, which responds well to traditional asthma medicines such as inhaled corticosteroids.2, 3
Severe Asthma. However, other studies seem to show that it’s sometimes non-allergic, associated with aspirin sensitivity, associated with neutrophilic inflammation along with eosinophilic, and sometimes associated with a sensitivity to aspirin. In such instances, it is less responsive to traditional asthma medicines like inhaled corticosteroids, meaning the highest doses are needed to obtain any degree of asthma control.2, 4
How do female hormones contribute to asthma?
Menstruation involves rises and falls in female hormone levels. This is important, because these rises and falls seem to have a direct effect on this subgroup of asthma. Before I delve further into explaining how this works, I think a basic understanding of the menstrual cycle is important. I will be very basic here. There are three phases.
- Follicular Phase. Levels of progesterone and estrogen are low. It begins when menstrual bleeding begins and usually lasts about 14 days, maybe a little longer. During this time follicles inside ovaries mature, rupture, and release estrogen. So, estrogen levels rise.2
- Ovulatory Phase. Elevated estrogen levels cause the release of an egg (ovulation). Estrogen causes changes in the female body, essentially preparing it for having a baby. At some point estrogen levels peak.2
- Luteal Phase. The phase begins when estrogen levels peak. The ruptured follicle that released the egg closes to form a corpus luteum, which releases another female hormone called progesterone. This does not occur if fertilization occurs. So, unless fertilization occurs, this phase begins right after ovulation and continues for another 14 or so days. It ends when progesterone levels drop, causing menstrual bleeding. Estrogen levels also drop.5, 6
So, many researchers believe premenstrual asthma involves the luteal phase, either when female hormones are at their highest, or when they are at their lowest.2 Keep this in mind as you read on, as many researchers believe this is where asthma symptoms are most likely to occur. But they’re not sure exactly the reason.
But there are a couple theories. So, what are they?
These rises and falls in female hormones are thought to be responsible for premenstrual asthma. To understand this, let’s take a look at female hormones along with some theories to explain how they might induce asthma.
It circulates through the bloodstream and binds with specific receptors in various cells of the body, including cells belonging to the lungs and immune system. This causes immune cells to release inflammatory markers that cause airway inflammation. This inflammation may be eosinophilic, resulting in allergies and allergic asthma. Airway inflammation is the hallmark of asthma, making airways hypersensitive (twitchy) in response to asthma triggers.3
A similar theory here is that estrogen causes bronchodilation, or that it opens airways to make breathing easy. This theory speculates that a sudden drop in estrogen at the end of the luteal phase may be what is responsible for airways becoming increasingly hypersensitive. So, as you can see, further research is needed in this area.3
Progesterone essentially prepares the body to take care of an embryo (an unborn baby), to make sure it has enough nutrients. Similar to the previously mentioned theory about estrogen, some researchers believe that it dilates airways, thereby keeping airways open when progesterone levels are high. Progesterone levels suddenly drop during the luteal phase when the egg isn’t fertilized. This, some researchers believe, causes a withdrawal period where airways become hypersensitive to asthma triggers.8
Another theory is that progesterone stimulates immune cells to release of chemicals (IL10, 1L1-b, TNF-a), which may cause eosinophilic inflammation and hypersensitive airways.2, 9
What is the best treatment?
It’s generally treated with traditional asthma medicines, such as rescue medicine like albuterol (Ventolin) and controller medicine like inhaled corticosteroids. It may also benefit from combination inhalers like Advair or Symbicort. Some studies show that Singulair may help. Some studies show that oral contraceptives, which prevent ovulation, may prove useful. It also may help to avoid Aspirin in those with a sensitivity to it.1-3, 9, 10
What to make of all this?
Premenopausal asthma is a relatively new asthma subgroup, so there is still much more to be learned. As you can see from my pithy review of it, there is more than one theory attempting to explain it. This may be confusing, but it’s a good kind of confusing. It means that researchers are looking for clues all over the place to better explain this asthma subgroup. As researchers learn more, they should be able to develop better treatment options for helping all asthmatics obtain ideal asthma control.
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