What is your surveillance protocol for patients with common variable immunodeficiency receiving chronic IVIG therapy?  

No target IgG level per se- dose/interval should be titrated to clinical condition. In general, trough  IgG on treatment should be higher than 500 mg/dL, or 500 mg/dL higher than baseline. Most patients will not be in optimal clinical condition (minimal fatigue, arthralgias, absence of chronic ...