Firstly, owing to insufficient ACTH, follicle-stimulating hormone, and luteinizing hormone released by the pituitary in the case of low levels of cortisol, estradiol, progesterone, and testosterone, as well as the effect of methylprednisolone, hypopituitarism was considered in our patient, which could be a possible etiology of his hyponatremia. The gene discussed is POMC; the disease is hypopituitarism.