Psoriatic arthritis (PsA) is an inflammatory form of arthritis. PsA is an autoimmune disease, meaning it is caused by the body’s immune system attacking healthy tissue, specifically, the joints and skin. This error of the immune system, therefore, causes inflammation in both the skin—which causes the rash flare-ups—and the joints—which leads to joint pain, stiffness and swelling.1
PsA is just one of many types of autoimmune disorders. In fact, there are more than 80 different types of autoimmune disease. Symptoms and treatment for these types of disorders may vary. But they all occur when the body’s immune system attacks healthy cells by mistake. And they all share a common pattern of inflammation flare-ups—when symptoms get worse—and remission—when symptoms get better.2
PsA and other autoimmune conditions
Though it is not known why, many patients with an autoimmune disorder have more than one. In fact, 25% of people with an autoimmune disease develop additional autoimmune diseases.3 One common autoimmune condition that can occur with PsA is thyroid disorder. But how often does a patient with PsA also have a thyroid disorder? And what is the connection?
What is thyroid disorder?
There are two main types of thyroid disorder: hypothyroidism and hyperthyroidism. Both are autoimmune conditions, but each cause different abnormal thyroid function.4 In hypothyroidism, the thyroid gland becomes underactive, which means the thyroid is unable to make enough thyroid hormone necessary to keep the body functioning. Symptoms can include feeling cold, fatigue, dry skin, depression, or constipation.5 In hyperthyroidism, the thyroid becomes overactive, and there is too much thyroid hormone being produced in the body. Symptoms can include nervousness, increased sweating, irritability, racing heart, hand tremors, trouble sleeping, thinning of the skin or hair, muscle weakness, or weight loss.6
PsA and thyroid disorder: Is there a connection?
Though both PsA and thyroid disorders fall into the category of autoimmune disease, there is some debate as to whether there is a connection between the two.7 Several clinical studies have aimed to examine whether thyroid disorder is more commonly present in patients with PsA. Some studies have found no statistical relevance between the two.7,8 Whereas, other research has shown an increased prevalence of thyroid disorder in patients with PsA and other rheumatic diseases.9,10
Though it is known that many patients with autoimmune disease often suffer from more than one, and both PsA and thyroid disorders are conditions related to a malfunctioning immune system. It is unknown if there is a direct relationship between the two. More research is needed to examine a possible connection between the two, as well as potential relationships between other autoimmune disorders.
Arthritis Foundation. What is psoriatic arthritis? https://www.arthritis.org/about-arthritis/types/psoriatic-arthritis/what-is-psoriatic-arthritis.php. Accessed February 6, 2019.
National Institutes of Health. MedlinePlus. Autoimmune diseases. https://medlineplus.gov/autoimmunediseases.html. Accessed February 6, 2019.
Benaroya Research Institute. Mystery of multiple autoimmune diseases. https://www.benaroyaresearch.org/blog/post/mystery-multiple-autoimmune-diseases. Accessed February 6, 2019.
Pincus, M. Rheumatology Advisor. Thyroid syndromes. https://www.rheumatologyadvisor.com/rheumatology/thyroid-syndromes/article/626390/. Accessed February 6, 2019.
American Thyroid Association. Hypothyroidism (underactive). https://www.thyroid.org/hypothyroidism/. Accessed February 6, 2019.
American Thyroid Association. Hyperthyroidisum (overactive. https://www.thyroid.org/hyperthyroidism/. Accessed February 6, 2019.
Khan SR, Bano A, Wakkee M, et al. The association of autoimmune thyroid disease (AITD) with psoriatic disease: a prospective cohort study, systematic review and meta-analyisi. Euro J Endo. 2017;177(4):347-350. https://eje.bioscientifica.com/view/journals/eje/177/4/EJE-17-0397.xml. Accessed February 6, 2019.
Chiriac A, Chiriac AE, Pinteala T, Foia L. Prevalence of thyroid abnormalities amont psoriatic patients. Endocrine Abstracts. 2014;35:262. https://www.endocrine-abstracts.org/ea/0035/ea0035p262. Accessed February 6, 2019.
Acay A, Ulu MS, Ahsen A, et al. Assessment of thyroid disorders and autoimmunity in patients with rheumatic diseases. Endo Meta Immun Dis. 2014;14(3):182-186. http://www.eurekaselect.com/122956/article. Accessed February 6, 2019.
Fallahi P, Ferrari SM, Ruffilli I, et al. Increased incidence of autoimmune thryroid disorders in patients with psoriatic arthritis: a longitudinal follow-up study. Immunol Res. 2017;65(3):681-686. https://link.springer.com/article/10.1007/s12026-017-8900-8. Accessed February 6, 2019.