CD40LG and Hyponatremia: In the cases analyzed, the most common features presented by IPSID patients were elevated serum IgA (39.5%) with α-heavy chain proteins (35.5%), low or normal serum IgM and IgG (17.1%), anemia (11.8%), lymphocytosis (6.8%), electrolyte disorder with hypokalemia and (9.2%) hyponatremia (1.3%), hypocalcemia (2.6%), and hypoalbuminemia (9.2%) (Table 3).