Celiac disease is an autoimmune condition where the immune system attacks the small intestine in response to gluten, a protein found in wheat, barley, and rye. About 1 in 100 people worldwide have celiac disease, yet roughly 80% of those affected remain undiagnosed. Unlike a simple food intolerance or preference, celiac disease is a serious medical condition that can cause lasting damage to the gut and trigger symptoms throughout the body if left untreated.

Why Is Celiac Disease So Often Missed?

One of the biggest reasons celiac disease goes undiagnosed for years, sometimes even decades, is that its symptoms are easy to mistake for other conditions. Fatigue might be blamed on stress, iron deficiency on diet, bloating on food intolerance, and brain fog on lack of sleep. Because celiac disease doesn't always present as a digestive problem, it can look entirely different from one person to the next, making it simple to overlook or dismiss until the underlying cause is finally identified.

For decades, medicine treated celiac disease as a rare childhood condition characterized by poor weight gain and chronic diarrhea. The reality is far more complex. The average time from symptom onset to diagnosis has historically stretched across years, sometimes more than a decade. This delay matters because undiagnosed celiac disease continues to damage the intestinal lining, preventing nutrient absorption and triggering a cascade of health problems.

What Happens Inside the Body When Someone Has Celiac Disease?

When a person with celiac disease consumes gluten, their immune system mistakenly identifies it as a threat and launches an attack. The problem isn't limited to targeting gluten itself; the immune system damages the body's own tissues, particularly the lining of the small intestine where food is digested and nutrients are absorbed. Over time, this attack destroys tiny, finger-like projections called villi that enable nutrient absorption, leading to intestinal injury and malabsorption.

The immune response involves the production of specific autoantibodies, such as antibodies that target tissue transglutaminase, an enzyme that modifies proteins including gluten. These immune responses fuel chronic inflammation and tissue destruction in the gut and can affect other parts of the body, contributing to symptoms such as anemia, bone loss, skin rashes, neurological changes, and fatigue.

What Symptoms Should Prompt Testing?

Celiac disease manifests differently in different people. Some experience classic digestive symptoms, while others have no obvious gut problems at all. The most recognizable symptoms involve the digestive system, but many people with celiac disease never experience obvious digestive symptoms. Instead, they may notice persistent fatigue, anemia that doesn't respond to iron supplements, or unexplained nutrient deficiencies.

Because celiac disease doesn't stay confined to the gut, the most noticeable symptoms for many people occur outside the digestive system entirely:

• Blood: Iron-deficiency anemia or deficiencies in vitamin B12 or folate
• Bones: Reduced bone density, known as osteopenia or osteoporosis, and increased fracture risk
• Skin: An intensely itchy, blistering rash called dermatitis herpetiformis
• Nervous system: Headaches, brain fog, peripheral neuropathy, or balance problems
• Reproductive system: Infertility or pregnancy complications
• Growth and development: In children, delayed growth or puberty
• General symptoms: Fatigue, often severe enough to disrupt work and daily routines

In some cases, these non-digestive symptoms are the only clues that something is wrong, making celiac disease easy to overlook until the underlying cause is finally identified.

What Genetic and Environmental Factors Trigger Celiac Disease?

Celiac disease develops from a combination of genetic and environmental factors working together. Almost everyone with celiac disease carries a specific genetic variant that affects how their immune system identifies threats. These variants, known as HLA-DQ2 and HLA-DQ8, influence how the immune system reads and responds to proteins like gluten. In people who carry these variants, fragments of gluten are more likely to be displayed to immune cells in a way that triggers an attack.

However, genetics alone don't cause celiac disease. Environmental triggers are also necessary. Certain infections, particularly gastrointestinal infections early in life, changes in the gut microbiome, or events that disrupt intestinal barrier function may help trigger the disease in genetically susceptible people, setting the stage for the immune system to overreact when gluten is encountered.

Celiac disease can appear at any age, but often emerges during periods of immune or physiological change, such as early childhood, puberty, pregnancy, or after major illness or stress. These shifts may influence immune regulation, tipping a balanced system into autoimmunity in people already at risk.

How to Manage Celiac Disease and Prevent Complications

• Get tested if you have symptoms: If you experience unexplained fatigue, anemia, nutrient deficiencies, bone loss, or any of the symptoms listed above, ask your doctor about celiac disease testing, which typically involves blood tests for specific antibodies and may include an endoscopy
• Eliminate all gluten from your diet: Once diagnosed, the only treatment is strict adherence to a gluten-free diet; even trace amounts from cross-contamination can trigger an immune response and intestinal damage
• Work with healthcare providers on nutrient replacement: Because celiac disease damages the intestinal lining and prevents nutrient absorption, your doctor may recommend supplementation for iron, vitamin B12, folate, calcium, and vitamin D until your gut heals
• Monitor for long-term complications: Left undiagnosed and untreated, celiac disease can cause lasting damage including malnutrition, weakened immunity, liver disease, and other serious health conditions

Dr. Padget Skogman, a board-certified pediatrician who lives with celiac disease herself, emphasized the importance of recognizing the condition's broader impact. "I was diagnosed with type one diabetes at the age of 5, but back then, celiac disease was barely heard of, let alone tested for yearly like it is today. It was my mom's diagnosis of celiac disease in 2008 that prompted me to get screened with an endomysial antibody test. I was 24 years old and had a history of microcytic anemia, but had no obvious GI discomfort. I was shocked when my test came back positive," she explained.

"As a pediatrician and a parent, I think about the mental health implications and risk for disordered eating for the kiddos who have to deal with a restrictive diet while growing up with celiac disease," Skogman noted.

Dr. Padget Skogman, Board-Certified Pediatrician

The key takeaway is clear: celiac disease is far more common than many people realize, and its symptoms extend well beyond digestive problems. If you experience unexplained fatigue, anemia, nutrient deficiencies, or any combination of the symptoms described above, discussing celiac disease testing with your healthcare provider is a reasonable next step. Early diagnosis and strict adherence to a gluten-free diet can prevent serious long-term complications and allow your intestines to heal.