What Acne Is
Skin and hair both are mostly comprised of a protein called keratin, and nourished with sebum, an oil naturally produced by the skin containing lipids and cell fragments. The normal flora on your skin’s surface use that sebum as food. Pores are the hair follicles in the skin.
When keratin cells multiply more than they should, they can cause the pore to narrow, which makes it easier for sebum to build up in the blocked follicle. The bacteria so often associated with acne, Propionibacterium acnes, is actually a normal part of the skin’s microbiome, but it is an opportunist. This means that it’s harmless as long as it stays on the skin’s surface. But when trapped in a blocked follicle, it can sets off your immune system’s inflammatory cascade and causes the infection known as acne.
Traditional over-the-counter treatments, such as benzoyl peroxide and salicylic acid, focus on killing the bacteria. More aggressive prescription treatments include steroids to decrease inflammation, changing the sebum chemistry and quantity (retinoids, from the Vitamin A family, and synthetic hormone-based treatments, such as birth control), and preventing the keratin cells from multiplying in the first place (also retinoids, like Accutane and isotretinoin).
All of these approaches can control symptoms, but they miss the root cause.
Causes of Acne
Common causes of acne include liver backup, hormone imbalance, high androgens, elevated blood glucose, and insulin resistance. Occasionally low essential fatty acids can play a role, as can low Vitamin D.
But sometimes, acne can be a symptom of hypothyroidism.
How Hypothyroidism Disrupts Vitamin A
All retinoid drugs are derived from Vitamin A. Vitamin A works by encouraging the regeneration of keratin in the skin (which is why it’s also in most anti-aging formulas).
However, the thyroid must be working properly in order to adequately convert carotenoids to Vitamin A.
There’s a feedback loop here, as well: once the Vitamin A status is low, hypothyroidism tends to worsen. This is because Vitamin A appears to be directly involved in the conversion of the less active T4 into the more active T3 hormone.
Progesterone and Your Thyroid
Progesterone is the sex hormone that helps to counterbalance estrogen, especially during that week or two right before your period. Too much estrogen relative to progesterone leads to breakouts.
There are two reasons why serum progesterone levels and hypothyroidism are inversely correlated. The first is that, as we’ve just seen, Vitamin A and hypothyroidism are inversely correlated, and adequate Vitamin A also encourages the body to produce progesterone. Therefore, if you’re hypothyroid, you have too little Vitamin A, and if you have too little vitamin A, you also have too little progesterone.
The second reason why hypothyroidism is linked to low progesterone is because progesterone facilitates the release of T4 from the thyroid gland. So again, it’s a feedback loop: hypothyroidism causes low progesterone, and low progesterone also perpetuates hypothyroidism.
If that weren’t enough, high estrogen levels also stimulate production of Thyroid Binding Globulin, or TBG. TBG binds thyroid hormones T4 and T3, preventing them from stimulating thyroid receptors. This means that even the T4 and the T3 that your body does manage to produce won’t do you any good. You’ll be functionally hypothyroid, even if total lab levels of T4 and T3 are still within range.
Androgens and Your Thyroid
Hypothyroidism also decreases Sex Hormone Binding Globulin, or SHBG. SHBG has the strongest affinity for testosterone, and a lower affinity for estrogen, but it does not bind progesterone at all; therefore, when SHBG is low, there is more testosterone and estrogen available to stimulate receptors. High testosterone levels can convert to dihydrotestosterone, or DHT: this is the androgen usually responsible for cystic acne.
Remember that the mechanism of acne involves 1) overproduction of keratin; 2) pores clogged with sebum; and 3) opportunistic skin bacteria causing inflammation within the clogged pore.
Hypothyroidism can be the root cause of acne on two of these. It can 1) decrease Vitamin A, thereby preventing the skin’s normal keratin regeneration process, and 2) render sebum more viscous through hormone imbalance, essentially increasing androgen and estrogen concentrations in the bloodstream while decreasing relative progesterone levels. Once either one of these processes have begun, they each self-perpetuate, worsening hypothyroidism, which in turn worsens both nutrient deficiency and hormone imbalance.
If you suffer from stubborn acne and have never had a full thyroid workup, including TSH, fT3, fT4, reverse T3, anti-TPO, and anti-thyroglobulin, I highly recommend you ask your doctor to check your levels!
While you’re at it, it’s a good idea to also request serum Vitamin A levels, and blood levels of the hormones progesterone, estradiol, and free and total testosterone. If you’re a menstruating woman with a regular cycle, the best time to check sex hormones is 7 days before your next period.