ALB and Hypoalbuminemia: A low PNI (defined by hypoalbuminemia and lymphocytopenia) further amplifies this pathological cascade: reduced albumin levels diminish plasma colloid osmotic pressure, exacerbating pulmonary edema (32); concurrently, lymphocytopenia impairs the phagocytic activity of alveolar macrophages, hindering effective clearance of pathogens within the alveoli (33).