Itchy Skin and Thyroid Autoimmunity
Published October 30 2017
Although having itchy skin (also known as pruritus) isn’t a classic symptom of either Graves’ Disease or Hashimoto’s Thyroiditis, it’s not uncommon for people with these conditions to have itchy skin. Sometimes people also experience rashes or hives, and other skin conditions such as eczema or psoriasis can also be present. But why do some people with autoimmune thyroid conditions experience itching of the skin, and what can they to get relief naturally?
While most people reading this are looking for a natural treatment approach to help relieve the itching they are experiencing, it’s important to understand why many people with Graves’ Disease and Hashimoto’s Thyroiditis have itchy skin in the first place. After all, while it would be great to just take some nutritional supplements and herbs to help with the itching, doing this alone many times won’t be sufficient.
The Four Categories of Itching
Believe it or not, there are four different clinical categories of itching (1) (2). Let’s take a look at these four categories below:
1. Neurogenic itching. This type of itch usually is caused by disorders that affect organ systems other than the skin, including chronic renal failure, liver disease, hematologic, and lymphoproliferative conditions and malignancies (2). This usually isn’t the cause of itching in those with Graves’ Disease and Hashimoto’s Thyroiditis.
2. Psychogenic itching. This type of itch is associated with psychological abnormalities and is considered to be psychiatric in origin. Once again, this usually isn’t the cause of itching in those patients with autoimmune thyroid conditions.
3. Neuropathic itching. This type of itching is related to the nerves, which in turn is caused by damage to the central or peripheral sensory neurons (2). In some cases this can be the result of the itchy skin, and sometimes the person will also have neuropathic pain.
4. Pruritoceptive itching. This type of itching is most commonly associated with those who have Graves’ Disease and Hashimoto’s Thyroiditis. It is generated in the skin either through inflammation or skin damage (2).
What Are The Different Mediators Of Itching?
Certain chemicals cause vascular and cellular changes. An example is histamine, as this is a chemical mediator released from cells during inflammation, which in turn causes vasodilation and increased vascular permeability. When it comes to itching, certain chemical mediators are involved. Let’s go ahead and look at some of the different mediators associated with itching (3).
Histamine. This is probably the most well known mediator, and it acts on H1 receptors that are present on C-nerve fibers. Histamine is a major factor in urticaria, although in many cases other mediators are involved. As a result, if someone takes a prescription or over-the-counter antihistamine, or a supplement that helps to reduce histamine levels such as quercetin, and if these don’t help to reduce the itching, then we can suspect that other mediators are also involved.
Acetylcholine. This is a neurotransmitter that can be responsible for some cases of itching. There is evidence that acetylcholine stimulates histamine C-nerve fibers (4), and also plays a role in itching in atopic dermatitis (5).
Cytokines. I’ve spoken about cytokines in past articles and blog posts, and there is evidence that an increase in the cytokine interleukin 2 (IL2) can result in itching (6) (7). There is also evidence that higher interleukin 6 levels can be a factor in itching (8).
Substance P. Substance P is secreted by nerves and inflammatory cells such as macrophages, eosinophils, lymphocytes, and dendritic cells and acts by binding to the neurokinin-1 receptor (NK-1R) (9). Substance P can increase inflammation, and it also regulates smooth muscle contractility, epithelial ion transport, vascular permeability, and immune function in the gastrointestinal tract (9). There are a few studies which show that higher levels of substance P can cause itching (10) (11).
Exogenous opioid agonists. There is evidence that exogenous opioid agonists can cause itching (12). An example is morphine, which is commonly used for pain management (12). Although morphine can cause the release of histamine from mast cells, this doesn’t seem to be its main mechanism in causing itching, as antihistamines don’t seem to be effective.
Prostaglandins. Prostaglandins play a key role in the generation of the inflammatory response. Prostaglandins apparently don’t directly cause itching, but further potentiate itching that is caused by histamine and other mediators (13).
Corticotropin-Releasing Hormone. Corticotropin-releasing hormone (CRH) plays a role in the release of ACTH from the anterior pituitary, which in turn leads to the release of cortisol. It is the major hypothalamic activator of the hypothalamic pituitary adrenal (HPA) axis (14). There is evidence that this hormone can cause itching through the release of histamine (15).
What Are Some of The Conditions Associated With Itching?
Now that you’re familiar with some of the mediators of itching, let’s go ahead and look at some of the conditions that are associated with itching:
Autoimmune skin conditions. It’s common for people with autoimmune conditions such as Graves’ Disease and Hashimoto’s Thyroiditis to experience itching. However, it’s important to keep in mind that itching isn’t a typical symptom of these conditions, although it’s common for people with autoimmune thyroid conditions to have skin conditions, which in turn can be responsible for the itching. In fact, there are separate autoimmune skin conditions that can cause itching including psoriasis, atopic dermatitis, scleroderma, dermatomyositis, epidermolysis bullosa acquisita, and Bullous pemphigoid. People with one autoimmune condition are more likely to develop one or more additional autoimmune conditions, which is why people with Graves’ Disease and Hashimoto’s are more likely to have skin conditions.
Dry skin. Dry skin, also known as xerosis cutis, can cause itching. Dry skin is a common complaint for those who have thyroid and autoimmune thyroid conditions, as it’s very common for my patients to put this down on their health history forms they complete prior to working with me. A thyroid hormone imbalance can be a factor, and while some people with hyperthyroidism and Graves’ Disease will experience dry skin, this is more common in those with hypothyroidism (16). When the dry skin isn’t related to the thyroid hormone imbalance it can sometimes be challenging to determine the cause of the problem. Nutrient deficiencies (i.e. omega 3 fatty acids) can play a role, but there can be other factors as well.
Cholestasis. This refers to an impaired secretion of bile, and itching is a complication of this condition, along with other conditions involving liver disease (17). Increased concentrations of bile salts, histamine, progesterone metabolites or endogenous opioids have been controversially discussed as potential causes of itching (18). The itching can be quite severe and even lead to sleep deprivation.
Chronic renal failure. This is a common cause of itching as well, and many people will have skin lesions due to the scratching (19). Those people undergoing dialysis are also likely to experience itching, although if someone has acute renal failure this is unlikely to cause itching (19).
Neuropathic Itch. Dysfunction of itch-sensing neurons can cause itching, although the cellular and molecular mechanisms are still unknown (20). Many neurological diseases cause pain, but sometimes they will cause itching instead of, or in addition to the pain (20). Unfortunately antihistamines are usually ineffective for this type of itching, as are corticosteroids and pain medications.
Certain medications. The administration of certain drugs can cause itching (21). This includes antihypertensive drugs, anticoagulants, some antibiotics, psychotropic drugs, and anti-epileptics (21). This doesn’t mean that these drugs will always cause itching, but if the itching started shortly after starting a new medication then this is something to consider. For those people with hyperthyroidism who take Methimazole, this sometimes can cause itching.
Diabetes mellitus. There is evidence that pruritus vulvae (itchiness of the vulva) is more common in those with diabetes mellitus, although generalized itching is probably not associated with this condition (22).
Conventional Treatments For Itching
So what are some of the conventional treatment options for itching? Well, it depends on the cause of the condition. For example, if someone is diagnosed with an autoimmune skin disease then they probably will be given antihistamines and/or corticosteroids. For those with hypothyroidism, many doctors will make the connection between low thyroid hormone levels and the dry skin, and if this is the case then they probably will recommend thyroid hormone medication to correct the thyroid hormone imbalance. If someone began to experience itching after taking medication then this probably will be looked into by most medical doctors.
I actually came across a table that showed a common conventional treatment approach in those who have chronic itching. It involves the following three steps:
Step #1: Diagnosis of the underlying cause, followed by general treatments (i.e. prevention of dry skin), along with symptomatic therapy (i.e. antihistamines, topical glucocorticosteroids).
Step #2: Specific treatment methods based on the cause of the chronic itching. For example, opioid receptor antagonists might be recommended if someone has cholestatic pruritus.
Step #3: Symptomatic topical and/or systemic therapy (i.e. capsaicin, calcineurin inhibitors, cannabinoid receptor agonists, gabapentin, UV-therapy).
Natural Treatment Solutions For Itchy Skin
What natural options are available for those who are experiencing chronic itching of the skin? Assuming you have ruled out any medications you’re taking as being a cause, here are a few things you should consider doing:
1. Follow an elimination diet. I commonly recommend this to my patients with Graves’ Disease and Hashimoto’s Thyroiditis, and I discussed this in a blog post I wrote entitled “The Elimination Diet and Thyroid Health”. This diet eliminates the most common allergens, which might play a role in itching.
2. Consider a low histamine diet. Since histamine can play a role in some cases of itching, it makes sense for some people who experience chronic itching of the skin to follow a low histamine diet. Some foods high in histamine include fermented foods (i.e. sauerkraut, pickles), alcohol, shellfish, smoked meat products, nuts, and legumes.
3. Reduce inflammation. One of the mediators of itching is cytokines, which play a role in inflammation. Prostaglandins are another mediator that play a role in inflammation. As a result, doing things to reduce inflammation can be necessary to eliminate chronic itching. This may sound easy enough, although at times it can be challenging to find the source of the inflammation. Some of the factors which can cause inflammation include infections, food allergens, environmental toxins, stress, and lack of sleep. You also want to eat an anti-inflammatory diet, and certain supplements might also help to reduce inflammation. This includes fish oils, vitamin D, turmeric, resveratrol, and ginger.
4. Heal the gut and improve immune system health. Of course healing the gut and improving the health of the immune system is essential for anyone with Graves’ Disease or Hashimoto’s Thyroiditis. And the same is true for someone who has an autoimmune skin condition that results in chronic itching. I have other articles and blog posts on this topic.
5. If dry skin is the cause then address this. As I mentioned earlier, dry skin is common in those with thyroid and autoimmune thyroid conditions. However, most of the time this doesn’t lead to chronic itching. With that being said, everyone is different, and it still makes sense to address this problem. If someone has dry skin and low thyroid hormone levels then the thyroid hormone imbalance should be addressed. If nutrient deficiencies are the problem then this of course should be corrected. While you can test for certain nutrient deficiencies, there’s nothing wrong with taking certain nutrients without doing any testing. For example, although there are fatty acid panels you can order, very rarely do I have my patients do this type of testing, as I have no problem recommending for most people to take an omega 3 fatty acid supplement.
6. Support the liver and kidneys. Since problems with the liver and kidneys can be a factor in some cases of dry skin, you might want to consider doing things to support these areas. From a dietary perspective this includes eating plenty of vegetables and drinking plenty of water. Supplements can also be beneficial in some cases, including milk thistle, NAC, dandelion, or an acetylated form of glutathione.
7. Supplements that reduce histamine. Earlier I mentioned some supplements that can reduce inflammation. You can also try taking supplements that reduce histamine. Quercetin is probably the most well known supplement that can help with this, although vitamin C is also something to consider. Diamine Oxidase (DAO) is an enzyme that breaks down histamine, and you can also get this in supplement form.
In summary, although having itchy skin isn’t a symptom found in everyone with Graves’ Disease and Hashimoto’s Thyroiditis, it is a common symptom. Chronic itchy skin can make people miserable, and in some cases can even interfere with sleep. Histamine is the most well known mediator of itching, although others include acetylcholine, cytokines, substance P, exogenous opioid agonists, prostaglandins, and corticotropin-releasing hormone. Some of the conditions associated with chronic itching include autoimmune skin conditions, dry skin, cholestasis, chronic renal failure, dysfunction of neurons, certain medications, and diabetes mellitus. If you are experiencing chronic itching you might want to start out by following an elimination diet, but other things you can do include follow a low histamine diet, do things to reduce inflammation, heal the gut and improve immune system health, address dry skin, support the liver and kidneys, and consider taking supplements that reduce histamine.