Celiac Disease Comorbidities: Conditions to Know About

Celiac disease travels with a surprisingly long list of other conditions, most of them autoimmune, and some affecting organs that seem to have nothing to do with the gut. The overlap is not coincidental: shared genetic susceptibility, chronic inflammation, and nutrient malabsorption each create pathways for disease well beyond the small intestine. Understanding which conditions tend to cluster with celiac disease matters for two practical reasons. It can speed up diagnosis when symptoms do not obviously point to gluten, and it can guide screening once a celiac diagnosis is confirmed.

Why One Autoimmune Disease Invites Others

The genetic machinery behind celiac disease does not operate in isolation. The immune-system genes most strongly linked to it, known as the HLA-DQ2 and HLA-DQ8 variants, are necessary but not sufficient on their own to cause the disease.¹ Those same gene regions also raise the risk of other autoimmune conditions. Beyond HLA, dozens of smaller genetic variants involved in immune regulation have been identified as shared susceptibility genes for both celiac disease and other autoimmune disorders, especially those affecting the endocrine system.² The result is that people with celiac disease carry a heightened genetic predisposition not just to one autoimmune disease, but to several. This shared genetic background explains why so many of the conditions discussed below are autoimmune in nature.

On top of genetics, the intestinal damage caused by untreated celiac disease increases permeability of the gut lining. When the barrier between the intestinal contents and the bloodstream becomes leaky, larger molecules cross into circulation and can provoke immune responses that would not normally occur.³ This mechanism likely compounds the genetic risk, turning a predisposition into active disease.

Type 1 Diabetes

Type 1 diabetes is one of the most studied companions of celiac disease. In the general population, celiac disease affects roughly one in a hundred people. Among adults with type 1 diabetes, the rate is substantially higher, with estimates ranging from about 2% to over 16% depending on the population studied and the diagnostic criteria used.⁴ The two conditions share the HLA-DQ2 and DQ8 gene variants, plus a number of non-HLA immune-regulatory genes. Because celiac disease in people with type 1 diabetes is often clinically silent, meaning no obvious gut symptoms, screening is widely recommended.⁵ Yet guidelines for when and how often to screen adults with type 1 diabetes remain inconsistent, and in one study only about 39% of adults with type 1 diabetes had evidence of serologic screening for celiac disease.⁴ Missing the diagnosis matters: untreated celiac disease in people with type 1 diabetes has been linked to lower bone mineral density, depression, and higher overall mortality.

Autoimmune Thyroid Disease

Hashimoto’s thyroiditis and Graves’ disease, the two main autoimmune thyroid conditions, show up frequently in people with celiac disease.⁶ Both involve immune cells attacking the thyroid gland, and both share the same HLA genetic risk region as celiac disease.² Hashimoto’s thyroiditis causes an underactive thyroid, leading to fatigue, weight gain, and cold intolerance, while Graves’ disease causes an overactive thyroid with symptoms like rapid heartbeat and weight loss. Thyroid symptoms can easily be mistaken for celiac symptoms or vice versa, so clinicians caring for someone with one condition should keep the other on their radar. This is especially true for Hashimoto’s, which is more common overall and may develop before, during, or after a celiac diagnosis.

Dermatitis Herpetiformis

If celiac disease has a signature skin condition, it is dermatitis herpetiformis. This intensely itchy rash shows up as small blisters and raised bumps, usually on the elbows, knees, buttocks, and scalp.⁷ Observational studies have consistently confirmed a strong clinical link between celiac disease and dermatitis herpetiformis.⁸

The rash is not a separate disease so much as an outgrowth of celiac disease itself. Gluten triggers the production of autoantibodies against a form of the transglutaminase enzyme found in the skin, and those antibodies deposit in the upper layer of the dermis, sparking inflammation.⁹ People with dermatitis herpetiformis almost always have intestinal damage consistent with celiac disease, even if they have no digestive symptoms. A strict gluten-free diet is the primary treatment, and the rash typically clears once gluten is fully removed, though it can take months.

IgA Deficiency and Diagnostic Complications

Selective IgA deficiency, where the body produces abnormally low levels of a key antibody class, is ten to fifteen times more common in people with celiac disease than in the general population.¹⁰ This matters because the standard blood tests used to screen for celiac disease measure the IgA form of certain antibodies. If you are deficient in IgA, those tests can come back falsely negative, making celiac disease look absent when it is actually present.¹¹

The workaround is to check total IgA levels alongside celiac-specific antibodies, and if IgA is low, to run the test using IgG-based antibodies instead. In children with selective IgA deficiency and symptoms suggestive of celiac disease, one study found the actual rate of celiac disease reached 20%, and IgG-based testing showed high sensitivity and specificity in that group.¹² If you have been told your celiac blood test was negative but you still have symptoms, it is worth asking whether your IgA level was checked.

Bone Loss

Low bone density and outright osteoporosis are among the most common complications of celiac disease, and in some cases, bone loss is the only sign that the disease is present at all.¹³ Two forces drive this. First, the damaged intestinal lining impairs absorption of calcium and vitamin D, both essential for maintaining bone strength. Second, the chronic inflammation of untreated celiac disease promotes the activity of cells that break down bone while suppressing those that build it.¹⁴ This applies to both adults and children.¹⁵

A gluten-free diet generally allows calcium absorption to recover, and bone density can improve over time, particularly in younger patients whose skeletons are still actively growing. Adults with long-standing untreated celiac disease may not fully recover their bone density, which is one reason early diagnosis matters so much. Bone density screening is commonly recommended for adults at the time of a celiac diagnosis.

Neurological and Psychiatric Manifestations

The brain and nervous system are not spared. Celiac disease has long been associated with neurological problems including cerebellar ataxia (difficulty with balance and coordination), peripheral neuropathy (tingling or numbness in the hands and feet), epilepsy, headache, cognitive impairment, and dementia.¹⁶ Neurological presentations are relatively rare in children but reported in up to about a third of adult patients.¹⁷ In some people, a neurological symptom is the first sign of celiac disease, appearing before any digestive complaints, which makes the connection easy to miss.

On the psychiatric side, depression and anxiety are common. One study found the lifetime prevalence of major depressive disorder was roughly 30% in people with celiac disease versus about 8% in controls, and panic disorder was also significantly more frequent.¹⁸ A separate survey of women with celiac disease found that about 37% met screening criteria for depression and about 22% for disordered eating.¹⁹ Associations with bipolar disorder and schizophrenia have also been noted, though these are less common.²⁰

The mechanisms probably involve a mix of nutrient deficiencies (particularly B vitamins and iron), neuroinflammation triggered by gluten-related immune activity, and the psychological burden of living with a chronic dietary restriction. Vitamin deficiencies caused by severe malabsorption can overlap with and worsen neurological symptoms like ataxia and neuropathy.¹⁷

Liver Involvement

Mildly elevated liver enzymes are a common finding in untreated celiac disease, sometimes called celiac hepatitis. The transaminase elevations tend to be modest and typically resolve on a gluten-free diet.²¹ In a smaller subset of patients, liver enzyme elevations persist despite strict adherence to a gluten-free diet. When that happens, an underlying autoimmune liver condition is often the cause. Celiac disease can coexist with primary biliary cholangitis and primary sclerosing cholangitis, among others. One study found a roughly 3% prevalence of primary biliary cholangitis in patients with celiac disease.²² If you have celiac disease and your liver tests stay abnormal after going gluten-free, further investigation is warranted.

Sjögren’s Syndrome and Other Rheumatological Conditions

Sjögren’s syndrome, an autoimmune condition that attacks moisture-producing glands and causes dry eyes and dry mouth, overlaps with celiac disease more than you might expect. Studies show that roughly 15% of people diagnosed with Sjögren’s syndrome also have biopsy-confirmed celiac disease.²³ A systematic review and meta-analysis examined celiac disease prevalence across several rheumatological conditions and found that primary Sjögren’s syndrome had the highest rate of biopsy-proven celiac disease, at about 5.6%. The pooled prevalence in systemic lupus erythematosus and systemic sclerosis was lower, around 3%, though seroprevalence of celiac antibodies in those conditions ranged from 3% to 10%.²⁴ The shared genetic background between celiac disease and Sjögren’s syndrome is well recognized, though current clinical guidelines do not always reflect it.²⁵

Microscopic Colitis

Microscopic colitis is an inflammatory condition of the large intestine that causes chronic watery diarrhea but looks normal on a standard colonoscopy, requiring biopsy to detect. It co-occurs with celiac disease in about 6% of cases, particularly among patients whose symptoms do not fully respond to a gluten-free diet.²⁶ This overlap is worth knowing about because persistent diarrhea in someone with celiac disease who is otherwise doing everything right on their diet can lead to frustration and diagnostic confusion. If a gluten-free diet is controlling most symptoms but watery diarrhea persists, microscopic colitis is one of the conditions clinicians should consider.

Reproductive Health

Untreated celiac disease has meaningful consequences for reproductive health. Evidence supports an association with adverse pregnancy outcomes, including a higher risk of miscarriage and restricted fetal growth.²⁷ A systematic review and meta-analysis found that undiagnosed celiac disease increased the risk of fetal growth restriction, stillbirth, preterm delivery, and lower birth weight, whereas women who had been diagnosed and treated with a gluten-free diet before or early in pregnancy did not show these increased risks.²⁸ The takeaway is clear: the harm comes from undiagnosed or untreated disease, not from celiac disease itself once it is managed.

Celiac disease may also affect fertility more broadly, although diagnosing this link is complicated by the fact that many women of childbearing age with celiac disease have not yet been identified. The effects on fertility appear to be reducible or even reversible with a gluten-free diet, but finding the women who need testing remains the biggest challenge.²⁹

Cancer Risk

The relationship between celiac disease and cancer is real but often overstated in popular coverage. The specific cancer most closely tied to celiac disease is enteropathy-associated T-cell lymphoma, a rare and aggressive type of non-Hodgkin lymphoma that arises in the small intestine. The adjusted odds ratio for T-cell lymphoma in people with celiac disease is high in relative terms, around 19 compared to the general population, but the absolute risk is still small because this type of lymphoma is extremely uncommon to begin with.³⁰ For non-Hodgkin lymphoma of any type, the relative risk is closer to about 3.³¹ Evidence suggests the risk is lower in people with milder or silent forms of celiac disease and in those who adhere to a gluten-free diet, likely because reducing intestinal inflammation over time lowers the long-term damage that promotes cancer.

Oral and Dental Signs

The mouth can provide early clues. Dental enamel defects, which show up as pitting, grooving, or discoloration of the permanent teeth, are significantly more common in people with celiac disease. A meta-analysis across 30 controlled studies found that celiac patients had roughly five to six times the odds of enamel defects compared to healthy controls.³² Recurrent mouth ulcers, known as aphthous stomatitis, also occur more frequently, with the same meta-analysis reporting about four times higher odds.³²

In one study of children, enamel defects were found in about 64% of those with celiac disease versus 16% of controls, and recurrent aphthous stomatitis was documented in about 28% of the celiac group.³³ Dentists who notice symmetrical enamel defects in a child’s permanent teeth, especially combined with recurrent mouth sores, have sometimes been the first to suggest celiac testing. The enamel damage, once present, is permanent because it occurs during tooth development, but a gluten-free diet can reduce the frequency of new mouth ulcers.

Growth and Development in Children

In early childhood, classic celiac disease tends to present with digestive symptoms and failure to thrive. But in older children, the picture shifts. Short stature and delayed puberty become more prominent presentations, sometimes without any obvious gastrointestinal complaints.³⁴ Chronic malabsorption interferes with the uptake of calories, protein, iron, and zinc, all of which are essential for normal growth. Catch-up growth typically occurs once a child goes on a strict gluten-free diet, though the degree of recovery depends on how long the disease went undiagnosed and how much growth potential remains.

Addison’s Disease and Polyglandular Autoimmunity

Addison’s disease, in which the adrenal glands fail to produce enough cortisol, can co-occur with celiac disease, though the combination is relatively uncommon, especially in children.³⁵ When Addison’s does appear alongside celiac disease, it is often part of a broader polyglandular autoimmune syndrome, where multiple endocrine glands are targeted by the immune system. This pattern reinforces the principle that a diagnosis of celiac disease should prompt awareness of other autoimmune conditions, particularly endocrine ones.

What Happens to Cholesterol on a Gluten-Free Diet

An underappreciated twist of the gluten-free diet involves lipid levels. Because untreated celiac disease impairs fat absorption, people with active disease often have lower-than-expected cholesterol. Once the intestinal lining heals on a gluten-free diet, fat absorption normalizes, and cholesterol can rise. A meta-analysis found that in adults, going gluten-free was associated with significant increases in total cholesterol (by about 12 mg/dL on average), triglycerides, and HDL cholesterol.³⁶ This is largely a sign of recovery, not a problem in itself, but it means that someone with celiac disease might see their lipid panel change in ways that look concerning if their doctor does not know the context. Pediatric patients showed a somewhat different pattern, with HDL going up but total cholesterol remaining stable.³⁶ In either case, the lipid changes should be interpreted in light of intestinal healing, and clinicians should not reflexively treat rising cholesterol as a new problem without considering the celiac context.