Celiac sprue is an autoimmune disorder in which eating gluten triggers an immune reaction that damages the lining of the small intestine. It affects roughly 0.7% to 2.9% of the global population. The term “celiac sprue” is an older name for the same condition now more commonly called celiac disease. You may also see it referred to as nontropical sprue or gluten-sensitive enteropathy.
How Gluten Triggers Intestinal Damage
Gluten is a protein found in wheat, rye, barley, and their crossbred hybrids like triticale. What makes gluten problematic for people with celiac sprue is its chemical structure. Gluten proteins are rich in a specific amino acid (proline) that makes them unusually resistant to digestive enzymes. In most people, this isn’t a problem. The partially digested fragments pass through without incident. But in genetically susceptible individuals, those fragments set off a chain reaction.
When gluten reaches the small intestine, it triggers the release of a protein called zonulin, which loosens the tight seals between intestinal cells. This allows undigested gluten fragments to slip through the intestinal wall into the tissue beneath. Once there, an enzyme modifies the gluten fragments by giving them a negative electrical charge. That charge is the key: it allows the fragments to lock onto specific immune receptors on the surface of cells, like a key fitting a lock. The immune system then treats these fragments as a threat, launching an inflammatory attack that destroys the tiny finger-like projections (villi) lining the small intestine. Those villi are responsible for absorbing nutrients from food, so their destruction leads directly to malnutrition and a wide range of symptoms.
Genetics and Risk
Celiac sprue requires a genetic predisposition. About 90% of people with the condition carry a gene variant called HLA-DQ2, while roughly 5% carry a variant called HLA-DQ8. The remaining 5% carry at least one of these two genes. People who are homozygous for DQ2, meaning they inherited the gene from both parents, face the highest risk, with more than five times the odds of developing the disease compared to the general population.
Carrying these genes is necessary but not sufficient. Many people have the genetic markers and never develop celiac sprue, which means environmental factors also play a role in triggering the disease. However, testing negative for both HLA-DQ2 and HLA-DQ8 effectively rules the condition out, making genetic testing a useful tool for excluding the diagnosis.
Digestive Symptoms
The classic presentation includes episodic diarrhea, abdominal pain, bloating, and weight loss. Infants typically show impaired growth, diarrhea, and a distended belly. Because the damaged intestine can’t absorb fat properly, stools may be pale, greasy, and foul-smelling.
These symptoms overlap significantly with irritable bowel syndrome, inflammatory bowel disease, diverticulitis, and intestinal infections, which is one reason celiac sprue often goes undiagnosed for years. Some people have mild or no digestive symptoms at all, making the condition even easier to miss.
Symptoms Beyond the Gut
Celiac sprue is not just a digestive disorder. Because it impairs nutrient absorption, it can affect virtually every organ system. Iron-deficiency anemia is common, sometimes severe enough to be the only noticeable sign. Bone weakness develops over time as calcium and vitamin D absorption drops. Nerve damage can cause tingling or numbness in the hands and feet.
Between 15% and 25% of people with celiac sprue develop dermatitis herpetiformis, an intensely itchy, blistering skin rash that typically appears on the elbows, knees, and buttocks. This rash is so closely tied to the disease that it can be diagnosed through a skin biopsy, and it resolves on a gluten-free diet just as the intestinal damage does. Chronic fatigue, infertility, and lactose intolerance are other common complications that may not immediately point to the small intestine as the source.
How It’s Diagnosed
Screening starts with a blood test that measures antibodies your immune system produces in response to gluten. The most widely used test looks for antibodies against tissue transglutaminase (tTG-IgA), which has both sensitivity and specificity above 90%. A second antibody test, endomysial antibodies, is particularly good at confirming the diagnosis because of its high specificity, meaning very few false positives.
A positive blood test is typically followed by an intestinal biopsy, which remains the gold standard. During an upper endoscopy, small tissue samples are taken from the lining of the small intestine and examined under a microscope. Pathologists grade the damage using the Marsh classification, a scale that ranges from Marsh 0 (normal tissue) through Marsh I (increased immune cells in the lining), Marsh II (added structural changes to the intestinal glands), and Marsh III (actual flattening and destruction of the villi). It’s important to keep eating gluten before testing, because going gluten-free beforehand can cause both blood tests and biopsies to come back falsely normal.
Treatment: The Gluten-Free Diet
The only established treatment for celiac sprue is a strict, lifelong gluten-free diet. This means eliminating all wheat, rye, barley, and their derivatives. In the United States, the FDA defines “gluten-free” as containing less than 20 parts per million of gluten, a threshold that applies to any food carrying that label. This includes foods that are inherently gluten-free (like rice or corn) as well as processed foods that have been manufactured to keep gluten below that cutoff.
For most people, removing gluten allows the intestinal villi to heal and symptoms to improve within weeks to months. Nutrient absorption gradually returns to normal. The skin rash of dermatitis herpetiformis also clears. The challenge lies in hidden sources of gluten: soy sauce, certain medications, malt flavoring, and cross-contamination during food preparation. Even small, repeated exposures can sustain intestinal damage.
What Happens if It Goes Untreated
Left untreated, celiac sprue leads to progressive malnutrition and a cascade of complications. Weight loss and nutrient deficiencies worsen over time. Bone density drops, increasing fracture risk. Nerve damage can become permanent. Infertility may develop in both men and women, and some of these advanced complications, particularly severe bone loss and reproductive damage, may not be fully reversible even after starting a gluten-free diet.
When the Diet Doesn’t Work
A small number of people continue to have symptoms and intestinal damage despite strict gluten avoidance for 6 to 12 months. This is called refractory celiac disease. It comes in two forms. Type 1 involves persistent damage but the immune cells in the intestinal lining still look normal under the microscope. These patients generally respond to immune-suppressing medications. Type 2 involves abnormal, clonal immune cells in the intestinal lining, which carries a significantly higher risk of progressing to a type of intestinal lymphoma. Refractory celiac disease is rare, but it underscores why follow-up testing matters even after starting a gluten-free diet.