An algorithm for the diagnosis of coeliac disease
| IgA-TG2 | Total IgA | IgG-TG2- | IgG-DGP | EMA | HLA | Biopsy showing CD type histology* | Coeliac status |
|---|---|---|---|---|---|---|---|
| Patient on a gluten-containing diet, IgA-TG2 or IgA-DGP, or IgG-DGP, EMA positive and the biopsy shows villous atrophy | Coeliac | ||||||
| For patients for whom the above criteria are not fulfilled, please see below | |||||||
| + | Normal or ND | ND | ND | ND | ND | + | Coeliac if VA, otherwise probably coeliac |
| + | ND | ND | ND | + | + | + | Coeliac if VA, otherwise probably coeliac |
| + | ND | ND | ND | + | + | − | Potential celiac† |
| + (usually low titre) | ND | ND | ND | − | − | − | Not coeliac |
| − | Normal | − | − | − | + | – | Not coeliac |
| − | Normal | – | − | − | − | − | Not coeliac |
| − | Normal | − | − | − | − | + | Unclear. Check serology when the patient is on a gluten-containing diet. Evaluate response to gluten-free diet, and consider other causes of VA |
| – | Normal | – | – | – | + | + | Unclear. Check serology when the patient is on a gluten-containing diet. Evaluate response to gluten-free diet, and consider other causes of VA |
| − | Low/absent | + | + | − | + | + | IgA deficient and celiac if biopsy shows VA. Otherwise IgA deficient and probable coeliac |
| − | Low/absent | − | − | − | − | − | IgA deficient, not coeliac |
| − | Low/absent‡ | – | – | – | + | + | ?post infectious diarrhoea Combined immune deficiency syndrome |
*Biopsy showing CD type histology = ±villous atrophy, ±crypt hyperplasia but must have intraepithelial lymphocytosis, IELs≥25/100 enterocytes.
†A duodenal biopsy may be negative when the lesion is only present in the jejunum.
‡And the patient does not respond to a gluten-free diet.
CD, coeliac disease; DGP, deamidated gliadin peptide; EMA, endomysium antigen; HLA, human leucocyte antigen; IEL, intraepithelial lymphocyte; ND, not done; TG2, transglutaminase 2; VA, villous atrophy (Marsh 3).