5 Top Causes of Hair Loss in Women: The Hidden Hormonal Triggers You Need to Know

The top causes of hair loss in women are not always clear, and may stem from a variety of hormonal triggers. Given just how distressing unexplained hair loss can be, it’s really important to explore the variety of possible root causes. Let’s walk through the top 5 hormones that may be the culprit.

The Hair Cycle

Hair follicles have a rather complex life cycle. The cycle of hair growth is split into different stages, with the most time spent in the growth (“anagen”) and resting (“telogen”) phases. 

The anagen growth phase lasts 2-8 years, while the telogen resting phase lasts 2-4 months. 10-15% of our hair at any given time is in the telogen resting phase and ready to be shed. 

One way that hormones can affect the hair cycle is by shortening the anagen growth phase and lengthening the telogen rest phase.

The hair cycle involves a wide variety of types of cells and different hormone signals. This includes epithelial stem cells, which are key in early hair growth, and are the same stem cells that are critical to maintain the integrity of our intestinal lining!

#1. Thyroid Dysfunction

Thyroid dysfunction can take different forms. Hypothyroidism refers to underactive or slow thyroid activity. Hyperthyroidism is the opposite, in which the thyroid gland is overactive. Thyroid autoimmunity results from the immune system attacking the cells of the thyroid gland.

Both hyperthyroidism and hypothyroidism can each result in hair loss. In fact, it’s estimated that 50% of those with hyperthyroidism, and 33% of those with hypothyroidism, experience hair loss.

It’s also common to see hair loss postpartum, in part due to thyroid activity. In what’s called postpartum thyroiditis, the thyroid gland goes from a hyperthyroid to a hypothyroid state. This boomerang effect is a major contributor to hair loss. 

Thyroid hormones are key regulators of hair follicle health. They are essential for early development and growth of hair follicles in utero. Thyroid hormones help promote and maintain the anagen growth phase, increasing the speed of new and existing hair growth. They also help regulate the length of the resting telogen phase, as well as hair shedding patterns.

Because hair loss can result from both under and overactive thyroid function, it’s important to get a complete thyroid lab panel to fully understand the state of your thyroid health. 

Thyroid related hair loss often begins with an increase in overall shedding both on the scalp and on other parts of the body, especially eyebrows and eyelashes. Changes in hair texture can also indicate potential thyroid dysfunction.

#2. Estrogen

We have estrogen receptors all over the body, including within the hair follicles of the scalp. Knowing this, it makes sense why high or low estrogen levels may impact hair growth and loss. 

Estrogen is known to be protective against hair loss. The best example of this can be seen during pregnancy, when estrogen levels are significantly higher than normal (alongside elevated progesterone levels), and women are often seen to have thicker, healthier looking hair.

That being said, high estrogen levels that are not balanced by adequate progesterone levels can result in what is often referred to as estrogen dominance. In the case of this imbalance, we actually can begin to see an increase in hair loss. There is research to suggest a link between estrogen and iron levels. While iron deficiency has been linked to hair loss, elevated iron levels and high estrogen have been linked and may also contribute to hair loss. . Link to estrogen and iron research and briefly mention that iron deficiency and excess can contribute to hair loss.

Let’s compare this to postpartum, when estrogen levels drastically decrease. This decrease in estrogen shifts hair follicles into the telogen resting phase, increasing the amount of hair loss. This postpartum hair loss is also known as telogen gravidarum. This shift can also happen as a result of other low estrogen states, such as during peri- and postmenopause, or after discontinuing estrogen-containing birth control.

If low estrogen is the culprit in hair loss, most times the frontal hairline is less affected than the rest of the scalp, and you may notice more overall hair thinning or shedding. Advanced hormone testing can help identify whether your estrogen and progesterone levels may be out of the optimal range.

#3. Androgens

Androgens, such as testosterone and its metabolite, dihydrotestosterone, or DHT, can cause hair follicles to shrink. This results in the growth of new hair that is shorter and thinner. As the follicles continue to shrink, they eventually stop producing hair. Usually we think of this pattern happening in men, causing baldness on the top of the head. However, elevated androgens have a similar effect among women and are a major cause of hair loss on the sides of the head. 

Elevated androgens and hair thinning or hair loss is a common characteristic among those with polycystic ovary syndrome (PCOS). We often see the pattern of elevated androgens coupled by either high or low estrogen levels in PCOS, which we know can both exacerbate hair loss.

While estrogen related hair loss doesn’t usually result in hair loss at the hairline, androgen driven hair loss does. In addition to overall hair thinning, you may experience an increase in hair loss along your hairline if excess androgens are to blame.

Rest assured, this is reversible. And research has shown that by decreasing excess androgen levels, hair loss can be effectively alleviated. We can do this by way of nutrition, lifestyle, and supplementation strategies. 

Figuring out if excess androgens are at play is crucial prior to implementing strategies that may alter androgens levels. Advanced hormone testing like the DUTCH Test gives insight into testosterone, DHEA, DHEA-S, DHT, and other androgens and androgen metabolites.  

#4. Insulin 

Insulin is our primary blood sugar regulating hormone in the body, transporting glucose from the blood into our cells. Insulin is released in response to increases in glucose, or blood sugar. When blood sugar is imbalanced, and we fluctuate between levels of high and low blood sugar, it becomes harder for the body to utilize insulin effectively to mobilize blood sugar. This is how insulin resistance develops.

Insulin resistance sets the scene for a variety of other health issues. It is a major driver of excess androgens, commonly seen in PCOS, which we know can contribute to hair loss. It also is a major contributor to oxidative stress, which negatively impacts mitochondrial function and every body system, especially hormone health.

Mineral insufficiencies and deficiencies affect how each of our body systems function on a cellular level. This also impacts our body’s ability to produce antioxidants. Without sufficient antioxidants, oxidative stress loads build, which can worsen insulin resistance. 

Essential minerals are required in larger amounts compared to trace minerals. Essential minerals like calcium and magnesium play major roles in insulin production and movement of glucose into our cells. Trace minerals like zinc, chromium, and selenium are also key for reducing insulin resistance and counteracting oxidative stress.

Ensuring adequate mineral intake through nutrition and supplementation is crucial for optimizing blood sugar balance, as mineral deficiencies or excesses themselves can also directly lead to hair loss. It’s also important to have an accurate assessment of your blood sugar and insulin sensitivity through testing that goes beyond just fasting glucose levels. 

#5. Cortisol

Cortisol, the body’s main stress hormone, is produced daily as part of our cortisol awakening response (CAR). It is also produced when our nervous system is activated. 

Elevated cortisol levels can impact the hair follicle cycle, preventing follicles from returning to the anagen growth phase after the telogen resting phase. This effectively puts the hair follicles into a dormant state. This is largely due to the fact that chronically elevated cortisol levels cause increased oxidative stress and inflammation. 

Low cortisol levels often are seen after long periods of high cortisol levels. This is because the adrenal glands downregulate their function in order to protect the body against the oxidative stress caused by chronically high cortisol levels. This is a key indicator of circadian rhythm disruption, which impacts hormonal signaling from the brain down to the ovaries. Along the way this can impact thyroid hormones, estrogen, and progesterone – all related to hair loss! 

Stress management is always the first step in helping regulate cortisol levels. We can also support cortisol levels, whether high or low, through nutrition, exercise, and supplementation strategies. Before implementing supplemental support to alter cortisol levels, it’s essential to understand your diurnal cortisol levels, or the 24-hour pattern of cortisol production. We can get this information from diurnal cortisol testing or the DUTCH Test.

Understand Your Triggers to Prevent Hormonal Hair Loss!

As you probably guessed, it’s important to get the appropriate testing in order to determine the root cause(s) of your hair loss! Check out our hormone testing packages, as a starting point to help you understand the potential triggers underlying your hair loss.

Written by Romana Brennan, MS, RD