*5.1.2.1 Serological tests*

Anti-tTG and anti-DGP have been used frequently to assess CD follow-up [76]. Use of these serological tests has revealed that it takes several months for the specific serology of CD to return to normal values. A significant decrease in levels during the first year suggests adherence to the diet and, therefore, patients with CD whose serology tests do not improve should be reassessed regarding their exposure to gluten [16]. However, negative serological markers do not reflect strict adherence to a GFD and are a poor predictor of dietary transgressions [17, 43, 77]. Although serology shows high accuracy for the diagnosis of CD, these tests are not as useful in follow-up, since they do not correlate with histological findings or symptoms [78]. It is important to note that a negative serology in a patient with CD on GFD does not necessarily


### **Table 1.**

*A comparison of the strengths and weaknesses of the tools used to monitor GFD in patients with CD. CD, celiac disease; GFD, gluten-free diet; GIP, gluten immunogenic peptides.*

guarantee the recovery of the intestinal mucosa [14, 43]. In a recent meta-analysis, PPV of persistently positive determination of anti-tTG IgA was very low and showed a sensitivity of 38% in adults. NPV of serology in adult patients with CD on GFD for one year or more was higher, with a specificity of 80%. Therefore, the usefulness of serology in the follow-up of adult patients with CD is very limited [1].
