Diabetes insipidus is caused by a deficiency in antidiuretic hormone which leads to excessive urination and water loss. Vasopressin is a synthetic antidiuretic hormone and is sometimes used for temporary treatment of diabetes insipidus. The amount of vasopressin used is titrated to the amount of fluids the patient receives and the amount of urine the patient produces, so tracking these things will be important. Vasopressin may cause a loss of sodium in the urine and subsequent hyponatremia (not hypernatremia). Vasopressin is only available via injection (IV, SubQ, IV). Vasopressin is known to lead to water intoxication, so the recommendation that it be taken with plenty of water is inaccurate.