February 14, 2011

Two of a Kind — Research Connects Celiac and Thyroid Diseases and Suggests a Gluten-Free Diet Benefits Both
By Cheryl Harris, MPH, RD, and Gary Kaplan, DO
For The Record
Vol. 23 No. 3 P. 24

Nature doesn’t always play fairly. Anyone with an autoimmune condition is predisposed to developing other autoimmune conditions, and there is a particularly strong connection between celiac disease and autoimmune thyroid disease (ATD), which includes Hashimoto’s and Graves’ diseases. Despite this connection, routine cross-screening is rare.

Since these conditions frequently lead to significant changes in weight, healthcare professionals are in a prime position to spot common symptoms and provide patients with potentially lifesaving testing and diagnosis. Understanding the connection between celiac disease and thyroid disease can help healthcare professionals design strategies for appropriate dietary management and support.

Background
About one half of the approximately 27 million people with thyroid conditions have not been diagnosed1, and almost 97% of the approximately 3 million Americans with celiac disease are undiagnosed.2

When an individual with celiac disease consumes gluten, an autoimmune process is triggered and the body attacks the villi of the small intestine, often leading to malnutrition. A similar autoimmune process occurs with ATD—except in this case, the target is the thyroid gland, producing a deficiency or excess of hormones and wreaking havoc on the body’s metabolism. The most common type of ATD is hypothyroidism, often caused by Hashimoto’s disease, which occurs most frequently in women during middle age and leads to a slowing of the metabolism. Graves’ disease is a hyperthyroid autoimmune process wherein the body attacks itself and the thyroid gland produces too much thyroid hormone.

Overlapping Symptoms
Celiac disease is often thought of as a gastrointestinal disease, with symptoms such as diarrhea, weight loss, bloating, and abdominal pain. While these symptoms usually present in young children, estimates indicate that approximately 70% of newly diagnosed people do not present with typical gastrointestinal symptoms.3

Symptoms of ATD and celiac disease often overlap, and many (eg, weight changes, fatigue) are nonspecific and incorrectly attributed to aging or depression. (See table for a summary.) While symptoms depend on whether thyroid function is overactive or underactive, patients with ATD often experience severe fatigue and changes in weight, bowel habits, and mood. Pregnant women, whose hormone levels change dramatically during the normal course of pregnancy, may experience a variety of problems due to untreated thyroid conditions.4

Research on the Celiac-Thyroid Disease Connection
People with celiac disease are more likely to develop ATD than the general public, and the reverse is also true. The increased risk holds despite treatment with a gluten-free diet or thyroid medications5 and may be due to overlapping genetic predispositions. In a recent study by Alessio Fasano, MD, a recognized celiac disease expert, one half of the people newly diagnosed with celiac disease also had thyroid disease.6 Most studies show a significant but much smaller association. The largest longitudinal study to date showed that adults with celiac disease had 4.4 times the relative risk of hypothyroidism and 2.9 times the risk of hyperthyroidism compared with the general public. In children, rates were higher still at 6 times and 4.8 times the risk, respectively.5

While just under 1% of Americans have celiac disease, recent thyroid review studies show that an average of 4.1% of adults with ATD have celiac disease7 and 7.8% of children with ATD have celiac disease.8 The authors of a review evaluating the usefulness of screening for celiac disease in patients with ATD concluded, “We believe that undiagnosed and untreated celiac disease may switch on some as-yet-unknown immunological mechanism that sets off a cascade of other disorders.”9

A 2008 study by Naiyer et al explored the connection between autoimmune hypothyroidism and celiac disease and hypothesized a mechanism via serum antitissue transglutaminase (tTG) antibodies. It is well established that anti-tTG antibodies are present in patients with active celiac disease and that they decrease and eventually disappear on a gluten-free diet. The study demonstrated that these anti-tTG antibodies bind and react to thyroid tissue as well, which may contribute to ATD development. Antithyroid antibodies were observed more often in patients with celiac disease than in either controls or patients with another autoimmune condition (eg, Crohn’s disease).10,11

Impact of a Gluten-Free Diet
As previously discussed, when individuals with celiac disease follow a gluten-free diet, their anti-tTG levels return to normal. A growing amount of research suggests that when people with celiac disease and ATD adopt a gluten-free diet, not only do their celiac-related antibody levels improve, but their thyroid antibody levels also decrease.12

A 2010 study in the Journal of Pediatrics found that 11 of 15 children with celiac disease who had elevated thyroid-stimulating hormone levels at diagnosis with celiac saw these numbers normalize after 12 to 18 months on a gluten-free diet.13 The Naiyer study noted that among people with celiac disease, significantly more people have thyroid antibodies before going gluten free than after (37.5% vs. 4.4%). The study also showed a positive correlation between anti-tTG and thyroid antibody titers in patients with active celiac disease.13 The only way to reduce anti-tTG levels is to eat a gluten-free diet. These studies suggest that a gluten-free diet has the potential to improve thyroid function by reducing autoimmune reactions in the body.

According to Mary Shomon, a nationally known thyroid advocate and author of The New York Times bestselling book The Thyroid Diet, “Hashimoto’s isn’t considered curable. Autoimmune diseases are usually lifelong. But for that subset of people that are triggered by underlying celiac disease or even gluten sensitivity, sometimes thyroid function goes completely back to normal. This only happens in a subset of patients, but some regain normal thyroid function and no longer need medication.”

Kathie Madonna Swift, MS, RD, LDN, a dietitian at the UltraWellness Center in Massachusetts, agrees: “We see a number of patients in our clinic who have [ATD] associated with both CD [celiac disease] and gluten sensitivity. Thus, if a patient has signs and symptoms of thyroid dysfunction, gluten should be on your clinical radar screen.”

Many clinicians report that eating a gluten-free diet may help improve thyroid function in nonceliac gluten intolerance. “Getting gluten out is primary for patients with Hashimoto’s, even without celiac disease,” says Diana Bright, MS, RD, CCN, CLT, of Bright Integrative Solutions in Golden, Colo. “I find that many of my clients feel better.”

And in patients experiencing malabsorption due to celiac disease, a gluten-free diet will alter absorption levels and can change the amount of thyroid and other medications needed.

Red Flags
Since celiac disease and ATD tend to lead to weight changes and fatigue and adopting a gluten-free diet often leads to weight gain, it’s easy for patients, dietitians, and physicians to incorrectly assign blame. “A lot of thyroid patients assume that if I’m tired, fuzzy brained, and puffy, it must be my thyroid. But if they are doing what they should be and have worked with doctors to optimize their symptoms, it’s time to look further at dietary factors like gluten or food sensitivities,” says Shomon.

Another red flag is when patients take increasingly large doses of thyroid medications and fail to have the expected response. Similarly, a detailed diet and exercise diary can indicate whether increases in weight are due to eating a highly refined, calorically dense gluten-free diet or whether thyroid problems or other conditions may be contributing, too. As a general rule, patients with autoimmune conditions who are continuing to experience unexplained symptoms despite the proper treatment may require further testing.

Invaluable Guidance and Support
Inside a medical record lie clues to potential health issues. For example, it’s possible the answers to why a patient is either unintentionally gaining or losing weight reside within the facts and figures garnered from office visits. Since most people with both celiac disease and thyroid conditions are undiagnosed, digging deep into the medical record can provide vital direction and ultimately help patients reach long-term weight and health goals. Recognizing and discussing the links between conditions and referring patients for further support and evaluation may be invaluable.

— Cheryl Harris, MPH, RD, specializes in celiac disease in Alexandria, Va. Gary Kaplan, DO, is founder and medical director of The Kaplan Center for Integrative Medicine in McLean, Va.

 

References
1. Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The Colorado thyroid disease prevalence study. Arch Intern Med. 2000;160(4):526-534.

2. University of Chicago Celiac Disease Center. Celiac disease facts and figures. Available at: http://www.celiacdisease.net/assets/pdf/CDCFactSheets FactsFigures v3.pdf

3. Guandalini S, Vallee PA. Celiac disease. Updated May 4, 2010. Available at: http://emedicine.medscape.com/article/932104-overview.Accessed June 20, 2010.

4. Alexander EK, Marqusee E, Lawrence J, et al. Timing and magnitude of increases in levothyroxine requirements during pregnancy in women with hypothyroidism. N Engl J Med. 2004;351(3):241-249.

5. Elfström P, Montgomery SM, Kämpe O, Ekbom A, Ludvigsson JF. Risk of thyroid disease in individuals with celiac disease. J Clin Endocrinol Metab. 2008;93(10):3915-3921.

6. Fasano A, Berti I, Gerarduzzi T, et al. Prevalence of celiac disease in at-risk and not-at-risk groups in the United States. Arch Intern Med. 2003;163(3):286-292.

7. Ch’ng CL, Jones MK, Kingham JGC. Celiac disease and autoimmune thyroid disease. Clin Med Res. 2007;5(3):184-192.

8. Larizza D, Calcaterra V, De Giacomo C, et al. Celiac disease in children with autoimmune thyroid disease. J Pediatr. 2001;139(5):738-740.

9. Berti I, Trevisiol C, Tommasini A, et al. Usefulness of screening program for celiac disease in autoimmune thyroiditis. Dig Dis Sci. 2000;45(2):403-406.

10. Naiyer AJ, Shah J, Hernandez L, et al. Tissue transglutaminase antibodies in individuals with celiac disease bind to thyroid follicles and extracellular matrix and may contribute to thyroid dysfunction. Thyroid. 2008;18(11):1171-1178.

11. Duntas L. Does celiac disease trigger autoimmune thyroiditis? Nat Rev Endocrinol. 2009;5(4):190-191.

12. Ventura A, Neri E, Ughi C, et al. Gluten-dependent diabetes-related and thyroid-related autoantibodies in patients with celiac disease. J Pediat. 2000;137(2):263-265.

13. Cassio A, Ricci G, Baronio F, et al. Long-term clinical significance of thyroid autoimmunity in children with celiac disease. J Pediat. 2010;156(2):292-295.