A treatment of the case with partial diabetes insipidus, accompanied by Rathke's cleft cyst, which was induced by polydipsia

A 42-year-old man was referred and admitted to the faculty of psychosomatic Medicine of Kyushu University Hospital because of polydipsia and polyuria in April 1994. He had been healthy until December 1993, when he began to drink a kind of 'ARUKARI ionic water', so called healthy beverage and had thirst, polydipsia, polyuria and palpitation. In early 1994, he could not take anything other than ice and water. He felt no taste at that time. So he began to drink more and more water because of his fiery thirst. In February 1994, he was diagnosed as having hyperthyroidism and became euthyroid under medication of thiamazole in a certain period. However, his polydipsia and polyuria never improved and his urine volume reached 7 l/day at the worst. After his admission in our hospital, the examinations showed that he suffered from partial diabetes insipidus and had Rathke's cleft cyst of 10 mm diameter in sella turcica. His polydipsia seemed to have begun because of his anxiety due to living in an isolated island and having a post surgical gait disturbance. Having had an explanation of his illness and a sodium restriction dietary, he improved his hypernatremia, higher plasma osmolality and lower urine osmolality. His signs also disappeared during the hospitalization of 2 months. In about a year after his discharge, plasma ADH also improved and the Rathke's cleft cyst naturally involuted and disappeared in the image of CT scan.