Figure 4.

Summary for measuring IgGSc concentrations as a monitoring tool. Normalization of IgGSc may support the diagnosis of THI and exclude suspicion of a more permanent antibody deficiency. The failure of IgGSc concentrations to normalize may be indicative of a more permanent IgGScD or the evolution of a more severe antibody deficiency. The antibody defect may remain IgGScD or develop further into other deficiencies. Examples may include accompanying a progressive deficient response to vaccines developing into clinically relevant IgGScD, development of low IgA alone with IgGScD, or the further development of low IgG or IgA in the progression to CVID.