This is a permanent allergy to gluten in the diet. If untreated, the disease may cause osteoporosis (thinning of the bones due to calcium deficiency). A blood sample may be taken to look for special proteins or antibodies (anti-transglutaminase) that develop in patients with untreated coeliac disease. Alternatively, the most effective diagnosis requires taking small samples from the small intestine at upper gi endoscopy and looking at these under a microscope. This condition can be managed effectively in the majority of patients by sticking to a 100% gluten-free diet indefinitely.