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DOI: 10.1055/s-0037-1612697
Autoimmune hepatitis with normal IgG at diagnosis: Subtype without selective elevation of IgG but similar histological features and treatment response
Publication History
Publication Date:
03 January 2018 (online)
Background:
The presence of selectively elevated IgG levels is a hallmark of AIH and has found its way into diagnostic scores. Nevertheless, about 15% of patients show normal IgG levels. The clinical significance of normal IgG values at diagnosis has so far not been explored in detail.
Methods:
We assessed biochemical, clinical and histological features from AIH patients with normal IgG-values at diagnosis. Data from 5 European high-volume centres were included. Liver histology was re-assessed by a reference pathologist to assure the diagnosis and compare histology in more detail.
Results:
In total, 130 patients with normal IgG-levels at diagnosis and an age- and sex-matched control group (n = 130) were included (Hamburg: n = 31, London: n = 51, Larissa: n = 30; Nijmegen: n = 9, Birmingham: n = 9).
No difference of fibrosis stage (2.3 ± 1.2 vs. 2.3 ± 1.3) or grading (3.0 ± 0.89 vs. 3.0 ± 0.93) according to Desmet and Scheuer classification was observed.
Besides higher IgG levels (IgG at diagnosis: 12.2 ± 3.2 g/L vs. 29.5 ± 5.8 g/L; p < 0.0001), patients with typical AIH had also a higher IgG/IgA ratio (9.3 ± 6.9 g/L vs. 5.4 ± 2.4 g/L; p<.00001) than patients with normal IgG at diagnosis. Moreover, the IgG/IgA ratio significantly decreased after initiation of immunosuppression (p<.0001), while it remained stable in patients with normal IgG at diagnosis. Of note, the IgG/IgA ratio was no longer different between study groups after 12 months of treatment (“typical AIH”: 5.8 ± 4.2 vs. “normal IgG”: 5.5 ± 2.2; p = 0.36).
Besides IgG and IgA, there was no difference in biochemical markers between groups at diagnosis, after 12 months under immunosuppression or at last follow-up.
Interestingly, 27% of patients with normal IgG values at diagnosis could be successfully weaned from immunosuppression, compared to only 13% in the control group (p = 0.027) and remained in remission for at least 2 years.
Conclusions:
Patients with normal IgG at diagnosis present with similar biochemical and histological features and show comparable treatment response, but show no selective elevation of IgG.