Thank you for your inquiry.
It is true that hyperlipidemia can produce spurious measurements of immunoglobulins if they are measured by nephelometry. You did not mention the lab procedure used in measurement of immunoglobulins at the laboratory you used, but I assume this was the technique utilized.
For your interest, I have copied below three links to websites discussing the potential interference with the measurement of immunoglobulins performed by nephelometry by hyperlipidemia.
Unfortunately, I do not think we can quantitate the degree of interference, and therefore cannot be sure whether or not in your case it would be clinically significant. Nonetheless, I think your approach to the patient is reasonable, and my suspicion is, based on the levels of his immunoglobulins cited, and his lack of protective titers to pneumococcus serotypes, that he does indeed have hypogammaglobulinemia.
I could find no reference that hyperlipidemia would contraindicate replacement therapy with immunoglobulins either by the intravenous or subcutaneous route.I was not aware of any such contraindication, and could find none on an Internet search. In addition, I reviewed the package insert of two immunoglobulin preparations, and neither listed hyperlipidemia as a contraindication. However, if you do institute immunoglobulin replacement therapy, and are still in any way concerned about his hyperlipidemia being a contraindication, I would look at the package insert of the specific preparation you plan to use.
Thank you again for your inquiry and we hope this response is helpful to you.
Interferences in Immunoassay
Immunoglobulin Free Light Chains, Serum
Phil Lieberman, M.D.