[Association of hyponatremia and eosinophilia: correlated idiopathic hypereosinophilic syndrome and SIADH or adrenal insufficiency with secondary eosinophilia].

A 56 year old man was admitted cause he had increasing symptoms as weakness, lethargy, disorientation. The total eosinophil count was 3000/mm3, the serum sodium concentration was 120 mmol per litre. In spite of severe hyponatriemia, urinary sodium excretion was not suppressed and serum osmolality (240 mOsm/Kg was lower than urine osmolality (488 mOsm/Kg). SIADH and Idiopathic Hypereosinophilic Syndrome was diagnosed because we found systemic failure signs due to hypereosinophilia (hepatitis, gastritis, pulmonary hypertension, and encefalopathy). Cortisonic treatment was started with symptoms improving, natriemia, eosynophil count and hepatitis signs normalization. After treatment stopping, reappeared asymptomatic hypereosinophilia, than we choosed Idrossiurea but, non-standing hypereosinophilia disappeared, appeared signs of preexisting adrenal insufficiency, emphasized by stopping cortisone therapy. A RMN showed an hypofiseal adenoma. Many cases of SIADH and Hypereosinophilia hiding adrenocortical insufficiency are reported with severe and unusual hypereosinophilia.