Changes in CO2 levels may suggest that someone is losing or retaining normal body fluids pointing to an imbalance in the body's electrolyte system. Lower than normal CO2 levels could indicate: Addison's disease, diarrhea, ketoacidosis, kidney disease, salicylate toxicity, lactic acidosis. Higher-than-normal CO2 levels could indicate: breathing disorders, Cushing's syndrome, hyperaldosteronism, respiratory tract infection.