sentence: days out of school / work ; number and duration of hospitalization ) establish the efficacy of IGSC 20 % in PIDD patients.To confer protection against infections in PIDD , serum IgG trough levels of > 5 g / l are generally accepted as the required minimum threshold ; for some patients , trough levels of at least 7 g / l may be necessary 25 , 26 , 27 .