Abstract: Objective To study the diagnosis of hypopituitarism manifested as hyponatremia in old patients.Methods Clinical data about 2 patients with hypopituitarism manifested as hyponatremia were retrospectively analyzed with its related literature reviewed.Results The 2 patients had a history of head and neck radiotherapy.The onset of their disease was insidious.Their main clinical manifestations were the atypical symptoms of hyponatremia.Symptoms such as asthenia and poor appetite were improved after hyponatremia was treated with replacement therapy.Conclusion Hypopituitarism can be manifested as hyponatremia in old patients and should be early diagnosed and treated.Medical doctors should improve their ability to recognize hyponatremia and pay their attention to the history of head and neck radiotherapy,and its etiological factors.