Hemodialysis: relationship between signal intensity of the posterior pituitary gland at MR imaging and level of plasma antidiuretic hormone.

Abstract

To investigate the correlation between signal intensity of the posterior pituitary gland on magnetic resonance (MR) images and levels of plasma antidiuretic hormone (ADH) in patients undergoing hemodialysis. The cases of 25 patients undergoing hemodialysis (15 men and 10 women, aged 24-75 years [mean, 51 years]) were prospectively evaluated. Laboratory testing and MR imaging were performed both before and after hemodialysis in 14 patients and only before hemodialysis in 11 patients. Before hemodialysis, nine patients (36%) had normal hyperintensity in the posterior pituitary gland, with almost normal plasma ADH levels and slightly elevated plasma osmolality. In six patients (24%) with less hyperintensity than is characteristic in the posterior pituitary gland, plasma ADH levels were slightly increased or normal. In 10 patients (40%) with an isointense posterior pituitary gland, plasma ADH and osmolality levels were evaluated. Elevated plasma osmolality may cause increased plasma ADH concentration and a lack of hyperintensity in the posterior pituitary gland at MR imaging.