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Systems in the human body are complex and interconnected, working in harmony to keep the body running smoothly. A change in one system can cause a ripple effect, impacting other systems, even if they initially seem unrelated. One surprising connection is the link between hypothyroidism and lymphedema, a condition that causes swelling in your arms and legs.
Hypothyroidism, an endocrine disorder, results from an underactive thyroid gland and leads to low thyroid hormone levels. Lymphedema, a condition of your lymphatic system, results in swelling of the extremities. While these two medical conditions may appear unrelated, research suggests some definite connections.
This article explores how an imbalance in your thyroid function can set the stage for developing lymphedema.
Lymphedema results from the build-up of fluid – called lymph – in your tissues. This condition is due to a dysfunction in your lymphatic system.
The lymphatic system is part of your immune system, which helps to prevent and fight infections. It consists of three main components:
- Lymph is a protein-rich fluid that flows between your cells. Lymph carries away germs, abnormal cells like cancer cells, and extra fluid.
- Lymphatic vessels are tiny tubes throughout your body that transport lymph in one direction - toward your heart. Damage or a blockage in these vessels affects the flow of lymph.
- Lymph nodes are collecting ducts that lymphatic vessels empty lymph into. Here, germs and damaged cells are filtered out of the lymph before it returns to circulation. Inside the lymph nodes are white blood cells that help kill germs and fight off infections. As your body fights off an infection, lymph nodes get bigger. You likely know that you have lymph nodes in your neck, but lymph nodes are located throughout your body.
As mentioned, an injury or blockage in your lymphatic vessels can cause lymph to build up. When this occurs, the affected areas will “balloon up” as more fluid accumulates. As a result, symptoms of lymphedema will start to appear, including:
- Swelling in your extremities, including arms, hands, legs, or feet
- Noticeable changes in your skin color
- A heavy feeling or pain in your extremities
- Decreased movement in affected joints
- Changes in how you feel certain sensations on your skin
- Tight-fitting clothes or shoes
- Recurrent cellulitis (skin infection), especially in those who are overweight or obese
The swelling is usually unilateral, meaning it only affects one limb. Sometimes ill-fitting clothes or shoes are the first noticeable symptom. As lymphedema progresses, both limbs may become impacted, depending on the underlying cause.
Lymphedema is classified as primary or secondary, with the significant difference being the underlying cause.
Primary lymphedema is an inherited condition resulting in the underdevelopment of the lymphatic system. Most of the time, there are too few lymphatic vessels in the legs. Because of this, those with primary lymphedema generally have leg swelling.
Primary lymphedema can occur at any stage of life, depending on when symptoms develop. Congenital lymphedema is when individuals are diagnosed at birth or before age two. Lymphedema praecox usually occurs in women around the start of their first menstrual cycle or pregnancy but can develop anywhere between the ages of 2 to 35. The third and final subtype, lymphedema tarda, develops after age 35.
Secondary lymphedema arises later in life due to damage to the lymphatic system. It is the most common type, accounting for 95% of all lymphedema cases. Damage could be caused by:
- Surgery, especially procedures related to breast cancer
- Radiation treatment for cancer
- Recurrent infections to the affected extremities
- Injury or trauma
How hypothyroidism affects your lymphatic system
Thyroid hormone is known for its role in regulating your metabolism, growth, and development. But, thyroid hormone also regulates your fluid balance and the makeup and function of your connective tissues, such as your muscles.
1. Fluid regulation
The lymphatic system and kidneys help maintain the body’s fluid balance. As mentioned, lymph carries extra fluid from your tissues to the bloodstream through the lymphatic vessels. Once in the bloodstream, blood flows through your kidneys, filtering out excess fluid.
Like all other cells in the body, the kidneys and the lymphatic system need thyroid hormone to function properly. A lack of thyroid hormone can prevent the kidneys from getting rid of extra water or how lymph flows throughout the lymphatic system. Both actions alter the fluid balance in your body, despite efforts to overcome dysfunction.
When pressure from the fluid between cells increases, lymphatic vessels enlarge. Bigger vessels allow for more lymph to flow through the vessel to carry away the extra fluid. But lymphatic vessels can only get so big, despite increasing amounts of fluid.
As lymphatic vessels stretch beyond their capacity or the surrounding tissues break down, they can become damaged. And as we now know, damage to the lymphatic vessels interferes with lymph flow. Because of this, extra fluid does not make it back into the bloodstream for elimination by the kidneys, resulting in lymphedema.
2. Tissue changes
Thyroid hormone plays a vital role in maintaining the health and function of your muscles. Under normal conditions, your muscles contract as needed to help you complete an activity such as walking or standing. But muscle contractions slow down in those lacking thyroid hormone, resulting in weak muscles and joint pain.
Lymphatic vessels rely on muscle contractions to move lymph through lymphatic vessels. And changes to the surrounding muscle’s elasticity or the strength of the contraction cans result in lymph pooling. As a result, lymph can build up in your tissues resulting in lymphedema.
Sometimes, and not always for clear reasons, the immune system mistakenly attacks healthy cells resulting in an autoimmune disorder. The primary cause of hypothyroidism in the United States is Hashimoto’s thyroiditis, an autoimmune disease.
In the case of Hashimoto’s, the immune system attacks healthy thyroid cells. As a result, thyroid cells are damaged or destroyed, causing low thyroid hormone levels and chronic inflammation.
A 2019 study showed that those with rheumatological autoimmune disorders had lymphatic impairment. Initially, the lymphatic system expands to help clear debris and inflammatory cells from the swollen area. But inflammation worsens when lymph can’t carry the waste and inflammatory cells away. As we now know, lymphatic vessels have a limited capacity. Over time, the lymphatic vessels become damaged from the ongoing inflammation and can no longer drain fluid effectively.
Researchers suspect chronic inflammation caused by autoimmune disorders like Hashimoto’s can contribute to lymphatic system dysfunction. Experts believe this is through changes in the structure and function of lymphatic vessels, resulting in symptoms of lymphedema.
Lymphedema is a chronic medical condition, meaning there is no definitive cure. But, with appropriate treatment for lymphedema, you can manage your symptoms or slow down its progression.
Lymphedema treatments focus on relieving the build-up of lymph in your affected limb(s). The degree of lymphedema will determine which therapy is most appropriate, with most requiring more than one treatment option. These therapies include:
- Manual lymphatic drainage: a process of elevating the limb and using gentle, rhythmic motions to push the lymph toward the heart
- Compression stockings or bandages
- Limb exercises
- Limb massage
In some cases, surgical management of lymphedema may be warranted. Surgeons can remove swollen tissues or create new passageways for the lymph to flow.
Studies have looked at the role acupuncture may play in reducing lymphedema. The thought is that by stimulating tissues around the lymphatic vessels, they will be better able to move fluid and inflammatory cells. But, evidence supporting acupuncture as a stand-alone therapy or in combination with standard lymphedema treatments is limited and conflicting.
Managing the underlying cause
For those with secondary lymphedema, it is necessary to address the underlying cause.
In the case of hypothyroidism, thyroid hormone replacement drugs will increase thyroid hormone levels. Treatment helps improve muscle contractions, fluid balance, and inflammation. These improvements aid in the management of lymphedema.
There are three thyroid hormone replacements medications that healthcare providers can prescribe:
- Levothyroxine (Synthroid, Levoxyl, Tirosint, and generics)
- Liothyronine (Cytomel and generic)
- Desiccated thyroid (Armour Thyroid, NP Thyroid)
Each medication contains one or both types of thyroid hormone and has unique side effects. Along with taking thyroid medication, there are lifestyle changes your healthcare provider may recommend to help manage hypothyroidism.
Have you noticed one shoe or pant leg isn’t fitting right, or are your extremities feeling heavier? It might be time to make an appointment with your healthcare provider. The earlier lymphedema is diagnosed, the better. The same is valid for hypothyroidism.
The first step to determining if hypothyroidism is potentially contributing to lymphedema is by testing your thyroid function. When using Paloma’s at-home testing kit, a simple fingerprick blood sample is all it takes to test your thyroid function. Paloma thyroid test kits measure the levels of the three main thyroid biomarkers used to diagnose hypothyroidism (Thyroid Stimulating Hormone/TSH, Free Thyroxine/Free T4, and Free Triiodothyronine/Free T3) as well as thyroid Peroxidase Antibodies (TPOAb) to test for the presence of an autoimmune thyroid disorder.
If your results show a thyroid disorder, our thyroid experts at Paloma Health can help you determine the next best steps. Our providers take a personalized, holistic approach to managing hypothyroidism.