 Cortisol also inhibits IgA in serum, as it does IgM; however, it is not shown to inhibit IgE.Cortisol increases glomerular filtration rate, and renal plasma flow from the kidneys thus increasing phosphate excretion, as well as increasing sodium and water retention and potassium excretion in high amounts acting as aldosterone (in high amounts cortisol is converted to cortisone which acts on mineralcorticoid receptor mimicking the effect of aldosterone).It also increases sodium and water absorption and potassium excretion in the intestines.