Kristen Gasnick, PT, DPT, is a medical writer and a physical therapist at Holy Name Medical Center in New Jersey.
Ana Maria Kausel, MD, is a double board-certified endocrinologist affiliated with Mount Sinai St. Luke's/Mount Sinai West in New York City.
About 30% of people with psoriasis, an inflammatory condition of the skin, develop an autoimmune, inflammatory form of arthritis called psoriatic arthritis. In psoriatic arthritis, the body produces autoantibodies, which attack its own joints. Psoriatic arthritis can result in permanent joint damage if left untreated.
The thyroid is an endocrine gland in the neck that produces thyroid hormones that control many metabolic processes in the body. When the thyroid is underactive, it doesn't make adequate levels of thyroid hormones.
An underactive thyroid (hypothyroidism) can be caused by medical conditions, most commonly by Hashimoto's thyroiditis. Hashimoto's causes inflammation of the thyroid gland that interferes with its ability to produce normal levels of thyroid hormones.
Psoriasis and Hashimoto's thyroiditis are autoimmune conditions—disorders in which the body's immune system produces antibodies that attack healthy cells. Because of this, psoriatic arthritis and thyroid problems frequently occur together.
This article will discuss how hypothyroidism affects the skin, how psoriatic arthritis may lead to hypothyroidism, and what you can do if you have these conditions.
SCIEPRO/SCIENCE PHOTO LIBRARY / Getty Images
While hypothyroidism isn’t a skin condition, inadequate levels of thyroid hormones can have a wide range of effects on the skin. These include:
Alternatively, when your body produces too much thyroid hormone, known as hyperthyroidism, psoriasis symptoms and associated skin plaques become worse. Treating hyperthyroidism often helps decrease the severity of skin-related psoriasis symptoms.
Related: Overview of Psoriatic Arthritis Rash
While hypothyroidism does not cause psoriasis or psoriatic arthritis, the conditions share similar underlying factors. Because of this, people with psoriasis and psoriatic arthritis may be more likely to have an underactive thyroid.
According to a 2021 systematic review (an analysis and summary of many studies to answer specific questions on a topic), higher levels of thyroid peroxidase antibodies and thyroglobulin antibodies have been reported in patients with psoriasis.
Thyroid peroxidase is an enzyme involved in producing thyroid hormones, while thyroglobulin is a protein found in the thyroid gland from which thyroid hormones are made. When the body produces antibodies to thyroid peroxidase and thyroglobulin, the thyroid gland becomes underactive when the production of thyroid hormones is blocked.
Clinical studies also suggest that the thyroid glands of people with psoriasis often appear hypoechoic (containing abnormal fatty nodules) when examined via ultrasound (imaging using sound waves). These thyroid nodules are often characteristic of hypothyroidism and occur more frequently in women.
Psoriasis and an underactive thyroid have a similar genetic characteristic, as the STAT4 rs7574865 genetic variation has been linked to psoriasis and autoimmune thyroid diseases.
Both conditions also share similar inflammatory markers (certain proteins detected in the blood in people with inflammatory disorders), including increased levels of cytokines IL-17 and tumor necrosis factor-alpha (TNF-alpha).
Both conditions are also linked to increased levels of reactive oxygen species (free radicals) that cause oxidative stress (antioxidants can't keep up with the free radical production) and alterations in cell differentiation and immune system response.
Because psoriatic arthritis and hypothyroidism result from increased levels of inflammation throughout the body, treatment aimed at lowering inflammation can be useful for treating both conditions. Enbrel (etanercept), for example, is a TNF inhibitor medication that is used to treat both psoriasis and thyroid conditions.
Taking a synthetic form of thyroid hormone called Synthroid (levothyroxine) is currently the standard treatment for patients with hypothyroidism. This medication is taken daily by mouth to restore normal levels of thyroid hormones to reverse hypothyroidism symptoms.
It is best to take levothyroxine by mouth on an empty stomach in the morning before you eat or take other medications. Certain supplements may interfere with your ability to absorb levothyroxine.
Be sure to talk to your doctor if you take any of the following as they may interfere with your hypothyroidism treatment:
Treatment with levothyroxine is usually very effective in managing symptoms of hypothyroidism. If you continue to experience symptoms despite taking your medication daily as prescribed, your doctor may increase your dose.
Because psoriatic arthritis and hypothyroidism can often occur together, it is important to screen for potential thyroid problems if you are diagnosed with psoriasis or psoriatic arthritis.
Regular blood work can be performed to check your thyroid hormone levels and evaluate your levels of antithyroid peroxidase antibodies to determine if your thyroid gland is functioning properly.
If either thyroid hormone levels or antibody levels are abnormal, you may need to have an ultrasound of your neck performed to examine the integrity of your thyroid gland.
Psoriatic arthritis and an underactive thyroid may occur together, since both may be due to underlying autoimmune inflammatory processes. Early screening, diagnosis, and treatment are key for effectively managing symptoms and preventing disease progression to promote optimal health and well-being.
If you have been diagnosed with psoriasis or psoriatic arthritis, talk to your healthcare provider about screening for an underactive thyroid. Stay on top of your treatment options for these conditions so you can maintain the best quality of life.
Most people notice symptoms of psoriasis, particularly dry, scaly skin plaques, before symptoms of psoriatic arthritis.
If you have already been diagnosed with psoriasis, the first signs of psoriatic arthritis typically include joint pain, warmth, and swelling, especially in the hands and feet, nail changes such as pitting and separation, and accompanying fatigue. Symptoms tend to come and go and worsen with flare-ups.
Psoriatic arthritis is not life-threatening, and many people with the condition live healthy and fulfilling lives. But psoriatic arthritis can negatively impact quality of life by causing joint pain, stiffness, and inflammation that can interfere with everyday activities.
Autoimmune conditions like psoriasis and psoriatic arthritis are often progressive–getting worse over time–especially if not diagnosed and treated early.
They can affect other parts of the body besides joints by causing inflammation. If not treated properly, psoriatic arthritis can cause significant health problems and disability.
Psoriatic arthritis can progress without appropriate treatment by affecting more joints on both sides of the body, most commonly affecting the hands, feet, and low back.
Psoriatic arthritis can also progress by worsening systemic systems (systems throughout the body), such as chronic fatigue; nail changes; tendon and ligament pain; inflammation of the eyes called uveitis; digestive symptoms such as abdominal pain, bloating, constipation, and diarrhea; and organ damage from inflammation to the heart, lungs, or kidneys.
National Psoriasis Foundation. About psoriatic arthritis.
American Academy of Dermatology Association. Thyroid disease: A checklist of skin, hair, and nail changes.
Eapi S, Chowdhury R, Lawal OS, Mathur N, Malik BH. Etiological association between psoriasis and thyroid diseases. Cureus. 2021;13(1):e12653. doi:10.7759/cureus.12653
Ruffilli I, Ragusa F, Benvenga S, et al. Psoriasis, psoriatic arthritis, and thyroid autoimmunity. Front Endocrinol (Lausanne). 2017;8:139. doi:10.3389/fendo.2017.00139
Benvenga S, Di Bari F, Vita R. Undertreated hypothyroidism due to calcium or iron supplementation corrected by oral liquid levothyroxine. Endocrine. 2017;56(1):138-145. doi: 10.1007/s12020-017-1244-2.
Dhir V, Aggarwal A. Psoriatic arthritis: a critical review. Clin Rev Allergy Immunol. 2013;44(2):141-8. doi:10.1007/s12016-012-8302-6
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