Celiac disease: How to correctly interpret the symptoms in adults

Do you often feel tired, unable to concentrate, or experience symptoms that no doctor can properly diagnose? These could be symptoms of celiac disease in adults . It's a complex autoimmune disorder that often hides behind everyday ailments and affects far more than just the intestines.

Why celiac disease in adults is often a chameleon

When people think of celiac disease, they usually picture the classic gastrointestinal problems. But especially in adulthood, the disease often presents a completely different picture. Imagine your body as a finely tuned orchestra: In celiac disease, gluten acts like a loud, disruptive noise that not only throws a single instrument group (your intestines) out of rhythm, but also disrupts the entire interplay.

The result is chronic inflammation of the small intestine lining, which severely restricts your ability to absorb nutrients. This deficiency in vitamins and minerals can then manifest itself in various areas of your body – often long before typical digestive problems even appear.

Understanding the hidden epidemic

The numbers speak for themselves. According to the German Celiac Society (DZG), approximately one in 100 people in Germany suffers from celiac disease. The interesting thing is that only about 10 to 20% of those affected exhibit the classic symptoms of abdominal pain and diarrhea.

The vast majority – around 80 to 90% – suffer from mild, atypical symptoms or initially experience no symptoms at all, which naturally complicates diagnosis. You can find more information on this topic in the AOK's information on celiac disease in adults .

This wide range of possible symptoms makes celiac disease a true chameleon among illnesses. Many sufferers have endured years of searching from doctor to doctor without receiving a clear answer. Often, symptoms such as chronic fatigue, iron deficiency, or joint pain are mistakenly dismissed as stress, signs of aging, or separate diseases.

Celiac disease is not just a digestive disorder. It is a systemic autoimmune disease that can affect your entire body – from your skin and joints to your brain.

More than just an intolerance

It's crucial to understand that celiac disease is far more than a simple gluten intolerance. While with an intolerance your body simply has difficulty digesting gluten, in celiac disease it triggers an aggressive immune response.

This reaction leads to the destruction of the villi in the small intestine – the tiny, finger-like projections responsible for nutrient absorption. You can learn more about the differences in our article on the various forms of gluten intolerance .

This guide aims to shed light on the subject. We'll show you which typical and, more importantly, atypical symptoms to look out for in order to better understand your body's signals.

Understanding classic digestive problems

Although celiac disease often hides well, the classic gastrointestinal symptoms are a key piece of the puzzle for many adults. Imagine the inner wall of your small intestine like a fluffy carpet with countless fine fringes. These fringes, called villi , greatly increase the surface area and ensure that nutrients from your food can be optimally absorbed into the bloodstream.

In celiac disease, gluten triggers a severe immune response that attacks the villi, the membrane lining the intestinal lining. The villi become inflamed, shorten, and eventually flatten completely. This dramatically reduces the surface area of ​​your intestine – a condition doctors call villous atrophy . The logical consequence: your body can no longer properly absorb vitamins, minerals, and other vital nutrients.

This state of impaired absorption is called malabsorption . It is the key mechanism responsible not only for problems in the intestines, but for many symptoms throughout the body.

From diarrhea to bloating

Digestive problems and chronic inflammation in the intestines lead to a range of typical symptoms. It's important to note that not everyone experiences all of these symptoms. The severity can vary drastically from person to person.

The most common classic digestive problems in adults include:

• Chronic diarrhea: Often watery, voluminous, and foul-smelling. It occurs because the damaged intestine can no longer properly absorb water and fats.
• Bloating and a distended abdomen: Undigested food particles slip into the lower sections of the intestine. There, bacteria feed on them and produce gas, leading to a painfully bloated abdomen.
• Abdominal pain and cramps: These are usually caused by gas and the constant irritation of the inflamed intestinal lining.
• Nausea and vomiting: This is less common, but can occur – especially after a meal containing gluten.
• Unexplained weight loss: If your body doesn't get enough nutrients despite a normal diet, it draws on its own reserves. This can lead to unintentional weight loss.

It's important to understand that these symptoms are a direct consequence of the inflammation and the resulting malabsorption. They are your gut's distress signal that something is fundamentally wrong.

When constipation becomes a symptom

It may sound paradoxical, but constipation can also be a sign of celiac disease. While diarrhea is much more common, some adults suffer from sluggish digestion instead. The exact mechanisms behind this are complex, but it is assumed that the inflammatory processes disrupt normal intestinal movement (peristalsis) and slow everything down.

It is precisely this variety of symptoms that makes differentiating celiac disease from other illnesses such as irritable bowel syndrome (IBS) so difficult. Many symptoms, especially bloating and abdominal pain, overlap. The crucial difference, however, is that celiac disease is an organic autoimmune disorder with demonstrable damage to the intestines. Irritable bowel syndrome, on the other hand, is considered a functional disorder without visible inflammation. A thorough medical examination is therefore absolutely essential to arrive at the correct diagnosis and finally begin the appropriate treatment.

Atypical symptoms: When celiac disease manifests outside the intestine

Without the classic digestive problems, many adults embark on a years-long, often frustrating odyssey from doctor to doctor. Celiac disease is a true master of disguise, and its symptoms in adults frequently appear in places you wouldn't initially associate with the intestines. In fact, these so-called extraintestinal signs are now the most common reason why the disease is diagnosed late.

Imagine the inflammation in your small intestine like a smoldering fire. At first, you might only notice the smoke spreading throughout the house—nonspecific symptoms—but not the fire itself. This "smoke" spreads through the bloodstream to the entire body and can cause problems in various places. The cause is a combination of the aforementioned malabsorption (impaired nutrient absorption) and a systemic immune response. So, your body isn't just fighting locally in the gut, but throughout your entire system.

When the energy has simply disappeared

One of the most common and, at the same time, most misinterpreted symptoms is chronic, debilitating tiredness and exhaustion , also known as fatigue. This is not the normal tiredness after a strenuous day. It is a deep, paralyzing feeling of energy depletion that persists even after sufficient sleep and is often mistakenly dismissed as burnout or a consequence of stress.

However, this fatigue has concrete, physical causes that are directly attributable to celiac disease:

• Iron deficiency anemia: Your body needs iron to transport oxygen through the blood. If the intestinal lining is damaged, it cannot absorb enough iron. The result: anemia, which leads to paleness, shortness of breath, and this severe fatigue. A typical sign is that iron supplements have little or no effect – because the iron simply doesn't reach where it's needed.
• Vitamin B deficiency: A vitamin B12 deficiency, in particular, can lead to fatigue and even neurological disorders. Since this important vitamin is also absorbed in the small intestine, a deficiency is almost inevitable in cases of undiagnosed celiac disease. If you want to learn more, read our article to better recognize the signs of a vitamin B12 deficiency .
• Chronic inflammation: Imagine your immune system is running at full throttle 24/7 to fight the gluten. This constant state of alert costs your body an incredible amount of energy – and you feel it every day.

The figures confirm this trend: The prevalence of celiac disease in adults in Germany has risen sharply in recent decades. A meta-analysis from 2020 shows that the incidence increased by an average of 7.5% annually. While the average age at diagnosis before 1981 was around 30, those affected are now often between 40 and 45 years old. This means that more and more adults are only becoming aware of symptoms such as fatigue, anemia, or osteoporosis in middle age.

When the mind and psyche suffer

The connection between our gut and our brain – the so-called gut-brain axis – is a fascinating field of research. In celiac disease, this communication is severely disrupted, which can manifest in a whole range of neurological and psychological symptoms.

Many sufferers describe a condition known as "brain fog." They feel unfocused, forgetful, and unable to think clearly. This is not imaginary, but a real consequence of the inflammatory processes and nutrient deficiencies that directly affect the brain.

Other possible symptoms in this area include:

• Headaches and migraines: Celiac disease can be a trigger for recurring, severe headaches. Many people report that attacks become significantly less frequent and less severe on a gluten-free diet.
• Depression and anxiety: Chronic inflammation can disrupt the production of important neurotransmitters in the brain, such as the "happiness hormone" serotonin. Added to this is the enormous psychological burden of years of unexplained symptoms.

Remember: If you are suffering from psychological or neurological symptoms for which no one can find an explanation, a close look at your gut and a possible celiac disease diagnosis could be the crucial step.

Skin, joints and liver as silent warning signs

The systemic nature of celiac disease is also evident in organs that you wouldn't initially associate with the intestines. The immune response and nutrient deficiencies leave their mark throughout the entire body.

A very specific skin condition closely linked to celiac disease is dermatitis herpetiformis Duhring . This is an extremely itchy rash with small blisters, often appearing on the elbows, knees, or buttocks. It is also known as the "skin manifestation" of celiac disease.

Joint and muscle pain can also be a warning sign. Chronic inflammation in the body can lead to nonspecific pain, which is sometimes mistakenly interpreted as rheumatism.

Finally, elevated liver enzyme levels can also be detected during a routine blood test, even without any other apparent cause such as alcohol or infection. The liver, as a central metabolic organ, is very sensitive to inflammatory processes. In many cases, these levels normalize on their own with a strictly gluten-free diet. This variety of possibilities makes it clear how important it is to consider unconventional explanations when experiencing unclear symptoms – and to keep celiac disease in mind.

The path to a reliable diagnosis

Do you recognize some of the described symptoms in yourself and wonder if you might have celiac disease? Then the next step is crucial: you need certainty. But how can such a complex disease be reliably diagnosed? The path to diagnosis is a clearly structured process consisting of several stages and absolutely requires medical supervision.

One thing is absolutely crucial: you must continue eating gluten-containing foods as normal throughout this process. This might sound strange, but it's absolutely essential. Think of it this way: if you want to catch a burglar in the act, locking the door beforehand won't help. It's the same with gluten. If you eliminate it before the tests, your immune system will suppress its reaction. The telltale traces in your blood and gut will become invisible – and the results would be inaccurate. A reliable diagnosis would then be impossible.

Step 1: The blood test as the first indicator

The process almost always begins with a blood test, also known as serology . The lab isn't looking for the gluten itself, but rather for the traces left behind by your immune system in its fight against it – specifically, for certain antibodies.

Your doctor will primarily look at these values:

• Transglutaminase IgA antibodies (tTG-IgA): This is the most important and informative marker. In celiac disease, the immune system mistakenly identifies the tissue transglutaminase enzyme as a threat and attacks it. Elevated tTG-IgA levels are a very strong indicator of active celiac disease.
• Endomysium IgA antibodies (EmA-IgA): This test is extremely specific and is often used for confirmation when the tTG-IgA test is positive.
• Total IgA: This value is checked in parallel to rule out a rare IgA deficiency. If someone had this deficiency, the IgA antibody tests would be falsely negative. In such a case, your doctor would switch to other testing methods (based on IgG).

A positive antibody test is not yet a definitive diagnosis, but it is the crucial spark that strengthens the suspicion and initiates the next steps. If you are unsure which tests are suitable for you, our article on celiac disease testing offers a good initial guide.

Step 2: Genetic analysis for exclusion

Sometimes a genetic test is also useful. This involves searching for the genetic markers HLA-DQ2 and HLA-DQ8 in blood or saliva samples. What you need to know: Approximately 30% of the population in Germany carries these genes, but only a tiny fraction of them actually ever develop celiac disease.

A positive genetic test result does not mean that you have celiac disease. It only means that you have the genetic predisposition for it.

The real benefit of the test lies in the opposite scenario: If neither HLA-DQ2 nor HLA-DQ8 is found in the genome, celiac disease can be ruled out with over 99% certainty . This makes it a valuable tool for finally providing clarity in cases of unclear findings or for family members of affected individuals.

The following infographic summarizes the typical path to diagnosis.

Here you can clearly see how the individual examinations interlock to ultimately arrive at a truly reliable diagnosis.

Step 3: Small bowel biopsy as the gold standard

The final and crucial step to definitively confirm the diagnosis is a small bowel biopsy . Even if the thought of it might cause some discomfort, the examination itself is usually straightforward and the only way to see the extent of the bowel damage with your own eyes.

The biopsy is performed during an endoscopy (gastroscopy). A specialist (gastroenterologist) inserts a thin, flexible tube with a camera through your mouth and esophagus into the first part of your small intestine. The entire procedure often only takes 10–15 minutes and can be performed under light sedation or light sleep if desired. You won't feel a thing.

During the endoscopy, the doctor takes tiny tissue samples (usually 4–6 ) from the lining of the small intestine. A pathologist then examines these samples under a microscope, specifically looking for the typical changes left by celiac disease.

• Villous atrophy: The intestinal villi are flattened or even completely absent.
• Crypt hyperplasia: The spaces between the villi are enlarged.
• Intraepithelial lymphocytes: A conspicuously large number of certain immune cells are found in the mucous membrane.

Only when the antibodies in the blood are positive and the biopsy confirms the characteristic damage to the intestinal villi is the diagnosis of celiac disease definitive. This clear, multi-stage process is essential because the consequence – a lifelong, strictly gluten-free diet – is a profound change that should only be undertaken on an absolutely sound basis.

Long-term risks of undiagnosed celiac disease

Celiac disease that goes undetected for years is far more than just a digestive problem. It's a ticking time bomb for your health. Imagine your body is constantly in a silent fight against it. The chronic inflammation in the intestines and the impaired absorption of nutrients leave their mark – throughout your entire body.

These consequences usually develop gradually. You won't notice them overnight. That's precisely why it's so important to be aware of the potential complications. This knowledge isn't meant to frighten you. Rather, it should encourage you to act quickly and seek clarity if you suspect symptoms of celiac disease in adults .

The domino effect of nutrient deficiencies

The intestinal lining damaged by celiac disease is like a leaky sieve. Essential building blocks for your body – vitamins, minerals, trace elements – are simply lost instead of reaching where they are needed. Sooner or later, this leads to serious deficiencies.

Two of the most common and consequential defects are:

• Iron deficiency and anemia: If your body can no longer absorb iron, you develop anemia. The result: You feel constantly exhausted, are pale, and have very little physical stamina. Persistent anemia that doesn't respond to iron supplements is a serious warning sign of undiagnosed celiac disease. You can find more information on this topic in our article about the importance of ferritin levels .
• Osteoporosis due to calcium and vitamin D deficiency: Strong bones need calcium and vitamin D. If these are poorly absorbed over many years, bone density decreases. This dramatically increases the risk of fractures in old age.

An undiagnosed case of celiac disease silently but steadily deprives your body of its most vital resources. The consequences often only become apparent years later, when serious damage has already occurred.

The increased risk for other autoimmune diseases

Celiac disease is an autoimmune disorder – and unfortunately, it rarely occurs in isolation. An immune system that has been misdirected tends to attack other structures within the body. These are then referred to as associated autoimmune diseases.

People with untreated celiac disease have a significantly increased risk of developing another autoimmune disease. The most common are:

• Hashimoto's thyroiditis: A chronic inflammation of the thyroid gland that leads to hypothyroidism.
• Type 1 diabetes: A disease in which the immune system destroys the insulin-producing cells of the pancreas.

Early diagnosis and a consistent switch to a gluten-free diet can calm the immune system and demonstrably reduce this risk. It's a crucial step towards regaining control of your health.

Effects on fertility and pregnancy

Family planning can also be severely disrupted by undiagnosed celiac disease – in both women and men. The chronic inflammation and nutrient deficiencies throw the delicate hormonal balance off.

In women, this can lead to menstrual irregularities, difficulty conceiving, and an increased risk of miscarriage. Men can also experience reduced fertility. The good news is that after diagnosis and starting a strict gluten-free diet, these problems almost always resolve completely.

These examples make it clear: Taking the symptoms of celiac disease seriously in adults and having them checked out is one of the most important preventative measures for your long-term health.

Why so many adults are unknowingly affected

Do you also wonder how such a profound illness as celiac disease can simply fly under the radar for countless people? The answer is actually quite simple: celiac disease is a master of disguise. The symptoms in adults are often so nonspecific and insidious that they are misinterpreted or simply accepted for years.

The old image of the typical celiac disease patient – ​​underweight, pale, and plagued by abdominal cramps – is long outdated. This stereotype now only applies to a small minority. Instead, many complain of vague symptoms such as debilitating fatigue, constant headaches, or unexplained joint pain. In everyday life, such symptoms are often quickly attributed to stress, lack of sleep, or simply aging.

Let's be honest: Who would immediately assume a serious bowel disease just because of persistent fatigue? This misconception leads to a huge number of undiagnosed cases. Celiac disease often smolders undetected for years, while your gut is already suffering silent damage.

The deceptive stillness in the stomach

A key reason for the often late diagnosis is the absence of classic gastrointestinal problems. If the abdomen isn't bothering the patient and digestion seems normal, neither those affected nor their doctors consider the intestines as the source of the problem.

In reality, the variety of atypical symptoms makes it so difficult. A persistent iron deficiency is treated with iron tablets, depressive moods with psychotherapy, and painful joints with painkillers. Often, only the symptom is treated, but the actual cause – the autoimmune reaction to gluten – remains undetected.

Many people still believe that celiac disease cannot exist without diarrhea or abdominal pain. This is a widespread misconception. Especially in adults, other symptoms often take center stage, distracting attention from the actual process occurring in the intestines.

This situation is underscored by a striking statistic: Estimates suggest that 80 to 90% of adults with celiac disease in Germany have no clear symptoms or only very mild ones. This means the vast majority are unaware of their condition. Textbook symptoms such as diarrhea or weight loss only appear in about 10 to 20% of those affected. You can read more about this astonishing number of undiagnosed cases in this article about celiac disease symptoms .

Understanding "silent celiac disease"

There is even a form known as silent celiac disease (or asymptomatic celiac disease). Those affected experience few or no symptoms subjectively. Nevertheless, their immune system is fully active, and the same destruction of the intestinal villi occurs in the small intestine.

This form of celiac disease is often discovered by chance – for example, during an endoscopy performed for a completely different reason, or when you are examined as a family member of a celiac patient. Even if you feel perfectly healthy, the damage to your intestines and the associated long-term risks are just as real. The absence of symptoms is therefore no reason to let your guard down. A medical evaluation for chronic, unexplained symptoms is always a sensible step to protect your long-term health.

Celiac disease symptoms: Your most frequently asked questions, briefly answered

Do you still have unanswered questions or are you unsure how to interpret certain signs? Here you will find clear and understandable answers to the most important points regarding the symptoms of celiac disease in adults .

Can celiac disease also occur in adulthood?

Yes, absolutely. Many sufferers only receive their diagnosis between the ages of 40 and 60. While you carry the genetic predisposition for it your whole life, it often takes a trigger to "awaken" the disease. This could be, for example, severe stress, a serious infection, or even surgery.

Will the symptoms disappear immediately if I eliminate gluten?

Unfortunately, not always. Some symptoms, like bloating or diarrhea, can often improve after just a few weeks. However, with other symptoms, such as iron deficiency, chronic fatigue, or neurological problems, it can take months before you notice a significant change. The regeneration of your intestinal lining is a process that takes time.

Patience is absolutely crucial here. Your body needs to heal the damage caused by chronic inflammation and slowly replenish its depleted nutrient stores.

If I suspect I have a gluten allergy, should I simply eliminate it from my diet?

Absolutely not – that's a misconception that can significantly complicate diagnosis. Self-administered gluten-free diets will distort the results of blood tests and small bowel biopsies. A subsequent, reliable diagnosis will then be almost impossible. Always consult a doctor before changing your diet.

Which doctor should I consult?

Your first step should ideally be to see your family doctor. They can order the initial blood tests (serology). If the suspicion is confirmed, a gastroenterologist is the right person to consult. They are the specialist for further diagnostics, in particular gastroscopy with biopsy.

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