After my third child was born in 2014, I could not get my body back to baseline. Months of symptoms piled up, and every appointment ended the same way. Another guess. Another dead end. A small-intestine biopsy finally confirmed what years of guessing could not. Celiac disease.

At the time, I assumed the diagnostic path was fixed and orderly. Symptoms, blood test, biopsy, answer. It took me years of reading to realize how recent each of those steps actually is. The blood test most doctors now order first was identified in 1997. The biopsy classification system was formalized in 1992. The rulebook I imagined as settled was still being written, and in some countries it still is.

I am not a physician, and nothing here replaces a conversation with yours. What I can share is what I learned from digging into the history and the current guidelines, because understanding where the diagnostic rules came from helped me understand why different doctors and different countries sometimes take different paths.

A Dutch doctor, a famine, and the first real clue

Willem-Karel Dicke was a Dutch pediatrician who made one of the most consequential observations in celiac research without a blood test or a microscope. During the winter of 1944 to 1945, the Netherlands was under German occupation and bread deliveries stopped. Dicke noticed that the children in his clinic who had been failing to thrive began to improve.

When bread returned after the war, he watched them relapse. He spent several years testing his suspicion: wheat was the trigger. His doctoral thesis, published in 1950, laid out the connection.

In that era, no diagnostic test existed for celiac disease. Diagnosis rested on clinical observation. A child who failed to thrive, improved on a wheat-free diet, and got sick again when wheat was reintroduced. This approach was slow, subjective, and only caught the most severe cases. Mild or atypical forms of the disease never made it onto a doctor's radar.

For decades, diagnosis meant a scope

A device called the Crosby capsule, introduced in 1957, let doctors take a small sample of intestinal tissue without surgery. By the 1960s, a duodenal biopsy showing villous atrophy, the flattening of the finger-like projections that line the small intestine, had become the diagnostic standard. In 1992, Michael Marsh published the classification system pathologists still use to grade those tissue samples today.

Biopsy was the definitive test for decades, and it brought precision. It also created a gatekeeping problem. An invasive test meant doctors ordered it only for patients with obvious, severe signs. Celiac disease in adults often shows up as anemia, fatigue, joint pain, or vague gut complaints rather than dramatic weight loss. Those patients went undiagnosed for years. Research from the Mayo Clinic and other centers confirmed what many patients already suspected: the average adult waited years between first symptoms and a correct diagnosis, and many were told along the way they had irritable bowel syndrome or stress.

A 1997 lab discovery changed the numbers

In 1997, a team led by Walther Dieterich identified tissue transglutaminase, commonly called tTG, as the specific target of the immune response in celiac disease. That discovery made possible the blood test now used as the usual first step: the IgA tissue transglutaminase antibody test, sometimes written tTG-IgA.

A 2016 meta-analysis in Clinical Gastroenterology and Hepatology reported tTG-IgA sensitivity of 93 to 98 percent and specificity of 95 to 98 percent. The test catches most cases of celiac disease and rarely flags healthy people incorrectly. Before this blood test existed, celiac disease looked rare because doctors only found the patients sick enough to be scoped. After it, researchers could screen large populations.

Those screening studies found celiac disease in roughly one percent of people across Europe and North America, far more than anyone had previously estimated. A 2003 multicenter study led by Alessio Fasano, published in Archives of Internal Medicine, found celiac disease in about 1 in 133 Americans. Most of those people had no idea they had it.

The test has a known blind spot. It relies on a normal level of immunoglobulin A, or IgA. The American College of Gastroenterology's 2023 clinical guideline notes that about 2 to 3 percent of people with celiac disease also have IgA deficiency, which makes the tTG-IgA result come back falsely negative. That is why a total IgA level gets drawn at the same time. For young children and people with IgA deficiency, doctors sometimes use a different blood test that looks for deamidated gliadin peptide antibodies, or DGP. An older test, the anti-endomysial antibody test, is more specific but requires a technician to read it under a microscope, so it is used less often for screening and sometimes as a confirmatory test.

Why some kids now skip the biopsy, while adults mostly do not

In 2012, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition, known as ESPGHAN, published guidelines allowing a celiac diagnosis without a biopsy in certain children. The criteria were specific. Symptoms consistent with celiac disease, a tTG-IgA level more than ten times the upper limit of normal, a positive anti-endomysial antibody test, and the presence of the HLA-DQ2 or DQ8 genetic markers. A 2020 update refined those criteria further.

The United States moved more slowly. The American College of Gastroenterology's 2013 guideline kept biopsy as the standard for adults. A 2023 update allows a biopsy-free diagnosis in selected adults with very high antibody levels, after shared decision-making with a doctor.

The reasons for the split are real. The biopsy catches the roughly 5 to 10 percent of people with celiac disease who have negative blood tests, a group called seronegative celiac, according to that same 2023 guideline. The biopsy also rules out other causes of villous atrophy and provides a baseline tissue sample for tracking healing later. Those concerns explain why many American gastroenterologists still want to see tissue before confirming a diagnosis. The counterargument is that an invasive test, with its cost, anesthesia, and waiting time, delays diagnosis for people the blood work already identifies with very high reliability.

What I wish someone had told me before my own diagnosis

Do not stop eating gluten before testing. If you suspect celiac disease and you cut gluten before any blood work or biopsy, the results can come back falsely negative. The American College of Gastroenterology recommends eating gluten for at least six weeks before blood work and at least two weeks before a biopsy. This is a conversation to have with a doctor before making any dietary change, because undoing a gluten-free diet for testing is its own kind of difficult.

Ask about total IgA. Since IgA deficiency affects about 2 to 3 percent of people with celiac disease, the standard blood test can miss those cases unless the lab also measures total IgA levels. This is a simple question that can save months of confusion.

Genetics can rule the condition out but cannot rule it in. About 30 to 40 percent of the general population carries HLA-DQ2 or DQ8, while almost everyone with celiac disease has at least one of those two markers. A negative genetic test is useful for putting celiac disease aside as a possibility. A positive genetic test tells you that you are in the at-risk group that needs further evaluation, nothing more.

None of this is a substitute for a physician who knows your full history. What the history gave me, though, was a clearer picture of why diagnosis can look different from one clinic to the next, and why some families get an answer in weeks while others wait years.

After the diagnosis, the kitchen becomes the rebuild

My own diagnosis came the old way: months of dead ends, then a biopsy. If you are in the middle of that process now, I will not pretend it is quick. The testing itself is more precise than it was in Dicke's era, but the waiting, the gluten challenge, the insurance questions, the second opinions remain hard.

What came after the diagnosis mattered just as much to me. That is why Clean Monday Meals exists, to put familiar, comforting food back on the table without gluten, dairy, or soy. The biopsy answers what is wrong. The kitchen is where meals start to feel normal again.

If you are newly diagnosed and trying to figure out what to eat, our free recipe app has hundreds of gluten-free and dairy-free recipes, with meal plans and grocery lists already built. You can find it at the Clean Monday Meals recipe app.