Can High-Dose Steroids Lower IgG Levels?
An adult female patient presented with a history of repeated severe asthma and anaphylactic episodes, and was treated with high-dose systemic corticosteroids (CCS) for months at a time. After a particularly long course of 80-120 mg of oral prednisone, she developed recurrent sinusitis and pneumonia, and was found to have hypogammaglobulinemia. Is there any known causative effect of high-dose steroids in lowering serum immunoglobulin (Ig)G levels?

Joyce Schoettler, MD

This is a very complicated patient. Recurrent anaphylaxis is a relatively rare problem, especially if no recognized cause is apparent. We do see patients with idiopathic recurrent anaphylaxis, and a study was conducted a few years ago at Northwestern University, Feinberg School of Medicine, Chicago, Illinois, that advocated high-dose, relatively long-term oral CCS for this disease.

I prefer to use a combination of oral H1 and H2 antihistamines twice daily (fexofenadine 180 mg + ranitidine 150 mg in the morning and cetirizine 10 mg + ranitidine 150 mg in the evening) as a treatment for recurrent anaphylaxis and only use oral CCS when absolutely necessary.

Long-term oral CCS do reduce IgG levels. The mechanism is unclear, but the patients who I have seen with low IgG levels on oral CCS tend to continue to have low IgG levels after the oral CCS have been removed. A few patients may recover normal IgG levels after stopping oral CCS, but many have persistent low IgG levels. Thus, although the CCS may be worsening your patient's problem, I wouldn't be surprised to see them remain a problem.

Can the patient make antibodies? We immunize such patients with pneumococcal vaccine and haemophilus B conjugate vaccine and check postimmunization antibody titers 2 months later. Even if the total IgG is low, what counts is antibody production. pneumococcal vaccine induces IgG2 antibodies and haemophilus B causes IgG1 antibody production. Thus, these immunizations allow you to determine the status of the patient's immune system. You can also use tetanus toxoid to check whether the patient can recall antigens and mount a response. If he/she makes a good antibody response, then it is likely that the IgG deficiency is not clinically significant.

If the IgG level is more than 10% below the lowest limit of normal in your laboratory, cannot make new antibody responses, and has recurrent bacterial infections, then IgG replacement may be considered. We only use IgG replacement to treat recurrent infections, most commonly sinusitis and bronchitis, in patients with clear-cut IgG deficiency and disease that do not respond to good medical management. However, when appropriate, IgG replacement is an extremely effective treatment. IgG is infused intravenously employing 400 mg/kg every month or so, and the treatment is continued thereafter.

Because Medicare is now reimbursing for the cost of IgG at a rate below what it costs to purchase, and temporarily paying hospital infusion centers nearly twice what they pay to private offices in my personal opinion, this may translate to increased cost to patients.