[CIS PIDD] 9 yo with CVID-like picture with persistent low IgG on IVIG

[Shayna Burke]

Colleagues,
We have a 9 yo boy with Down Syndrome that was diagnosed with hypogam/CVID like picture a little over a year ago, whom we cannot get IgG levels above 200s.  He has a history of recurrent pneumonias and sinusitis and was found originally to have the following labs:
IgA 74, IgM 32, and IgG 241 (nl 580-1256), and had 1/14 protective pneumococcal serotypes. 
He was given pneumovax and 2 months later his labs showed:
IgA 62, IgM <25, IgG216.
Tetanus was protective at 0.6 and diphtheria was also at 0.05.  He continued to only have 1/14 protective pneumococcal titers.
He was started on Gammagaurd liquid at 500mg/kg/dose in March 2011 and has gotten IVIG every 28 days since then.  However, we have not been able to get his trough out of the 200s (ie the troughs have been 203, 252, 203, and 278).  We have increased his dose due to these troughs and he is now up to 1.25grams/kg/dose and this resulted in the most recent IgG trough of 278 (also now has normal IgA and IgM).  Along with this most recent trough, we did obtain titers to see if he is maintaining any protection from the IVIG, but he had no protection to Varicella (IgG negative) and 0/14 protective pneumococcal sterotypes.  He does not have diarrhea, and actually has constipation that requires a laxative every other day.  He is not edematous.  The family is not interested in SCIG or coming in more frequently for infusions.  Clinically, he is doing well and has not had any pneumonias since starting IVIG .
Questions for the group:
1)Any suggestions on if we should continue to push the dose or back down due to possible inhibition of B cells at this high of doses?   What would you recommend we do for this patient?
2)Any suggestions of possible etiologies for where his IgG is going or why we cannot get his trough up?
Thank you very much for your help.
Sincerely,
Shayna Burke, MD
Fellow, Allergy/Immunology
Children’s Hospital of Pittsburgh
 
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