The clinical picture of celiac disease covers a wide range, from people with no symptoms at all to those with severe malabsorption. Recognising where a patient sits on that range starts with the terms used to describe the forms of disease.
Terminology
- Classical celiac disease — CD manifested by malabsorption, steatorrhea, weight loss and nutritional deficiencies.
- Non-classical celiac disease — CD manifested by anemia, fracture risk, infertility or abdominal bloating.
- Potential celiac disease — the presence of serological findings of CD without any intestinal changes on biopsy.
- Non-responsive celiac disease (NRCD) — signs and symptoms of CD in a recurrent form despite adherence to a gluten-free diet (GFD) for more than 6-12 months.
- Refractory celiac disease (RCD) — severe signs and symptoms with severe intestinal involvement despite adherence to a GFD for more than 6-12 months.
The spectrum of presentation
Manifestations range widely, from asymptomatic to frankly symptomatic with severe malabsorption and malnutrition. Asymptomatic patients are usually diagnosed when they have relatives with CD and are referred for screening, or when they have other associated conditions such as:
- Down syndrome
- autoimmune thyroid disorders
- hematological disorders
- musculoskeletal disorders such as osteoporosis
- liver disorders, with increased liver aminotransferases
- neurological disorders such as peripheral neuropathy
This is why a low threshold for testing is useful in these groups: the disease can be present and causing silent nutritional damage long before it produces a symptom. At the other end of the spectrum, the classic malabsorptive picture develops when enough of the small bowel is involved that absorption of fat, protein and micronutrients fails.
Presentation in children
The presentation of CD in infants is classically with diarrhea, steatorrhea, abdominal distension and cramps, and abdominal pain. Children with undiagnosed CD are not able to thrive, which can lead to short stature; initiation of a gluten-free diet is followed by increased growth in these patients. In older children with CD the common manifestation is anemia. In the past celiac disease was considered a pediatric condition, but in recent years diagnoses of CD in older adults have increased, with a peak age in the 5th decade of life, so the disease should not be excluded on age alone.
Gastrointestinal manifestations
The gastrointestinal manifestations of celiac disease can be tremendously variable between adults, but the most common is diarrhea. It is usually watery and mostly episodic, and the episodes tend to be nocturnal, early morning and post-prandial. Loss of protein with severe diarrhea can lead to hypoproteinemia and consequent edema, and in patients with severe celiac disease with involvement and damage to the proximal small intestine there is electrolyte wasting and secretion into the lumen. In severe diarrhea there is hypokalemia, which can cause severe muscle weakness.
Steatorrhea is an important qualifier: it is absent in patients who have disease limited to the proximal small intestine, so its presence points to more extensive involvement. Bloating with vague abdominal pain is very common in CD and mostly leads to a misdiagnosis of IBS (irritable bowel syndrome); because diarrhea-dominant IBS and celiac disease resemble each other in terms of bloating, IgA anti-tTG testing is suggested in all patients diagnosed with IBS. Abdominal cramp and distension also occur. Severe abdominal pain is different — it suggests a complication such as intussusception, ulcerative jejunitis or intestinal lymphoma, rather than uncomplicated disease. Pancreatic insufficiency is common in active celiac disease, which can be due to impaired secretion of CCK (cholecystokinin) and secretin in response to a meal. Nausea and vomiting are very rare.
Aphthous stomatitis can be the only manifestation of celiac disease in some patients.
Extra-intestinal manifestations
As patients get older, celiac disease manifests its consequences in organs other than the gastrointestinal tract, mostly because of the nutritional malabsorption. Anemia is a common manifestation in both children and adults, and is mainly caused by the malabsorption of iron and folate; in the presence of vitamin K deficiency and consequent bleeding disorders the anemia is worsened.
Low bone density is another common consequence. Osteopenia is a common complication of CD, and more than 70% of untreated CD patients have osteopenia, while more than 25% have osteoporosis. Both occur because of the lack of absorption of calcium and vitamin D; with prolonged hypocalcemia there can be secondary hyperparathyroidism, which leads to further mobilisation of calcium from bone into blood and further worsens the bone mineral density.
Neurological and reproductive complications round out the picture. Gluten ataxia is a condition in which there is damage to the cerebellum, the posterior column of the spinal cord and the peripheral nerves, and night blindness is caused by vitamin A deficiency. Gynecological problems are common in women with CD, and the binding of anti-tTG to trophoblast cells is suggested as the cause of the infertility and poor outcome of pregnancy in women with CD.
The severe end of this spectrum — celiac crisis, refractory disease and intestinal lymphoma — is covered in Complications of Celiac Disease.