There are two diagnoses types test the first one is the serology consits on a blood test and they detrermine if there exist antiendomisions antibodies ( a type of antybody that protects us from gluten), antigladine antibodies ( is an antybody that are generated by the inmune system too prevent gliadine) and antitraglutaminase antibodies. 

The second part of serology determine the level of minerals in the body of adults and kids those minerals are: iron calcium magnesium folates and transaminases 

The other is an intestinall biopsy, after an endoscopy ( view of the cavity and tubes of the human body). To detect the gluten intolerncy there is an escale, called Marsh escale, it has four level. 

-First level: in our organism it must bbe 30 linfocits per 100 epitelial cells, so in this level of linfocits start increasing. 

-Second level: thos linfocits that are increasing start making biggers. 

-Third level: at this level is when the doctors exactly know if you have an intolerance. In this level the continue the same problem that in the first and second level but here the intestinall villi start getting smoother. This is called intestinall atropphy 

-Four level:is not very common on this level the intestinall villi is competly crushed. 

If you make a gluten diet and you fell better duriiing 12 or 18 months you must know that you have a intoleracy to the gluten.