[Inappropriate ADH secretion syndrome and hypereosinophilia in Horton disease with stenosis of the subclavian arteries].

The authors describe a case of giant cell arteritis with subclavian involvement in association with a syndrome of inappropriate anti-diuretic hormone secretion and hypereosinophilia. Subclavian involvement, which may be the first symptom, occurs in five to twenty percent of giant cell arteritis. Hypereosinophilia, a frequent manifestation of specific granulomatosis vasculitis, is rarely described in association with giant cell arteritis. Dysfunction of the hypothalamo-pituitary axis such as inappropriate anti-diuretic hormone secretion or diabetes insipidus has been recently reported in giant cell arteritis. The syndrome of inappropriate anti-diuretic hormone secretion may either reveal the disease or occur during the evolution, in particular with gradual reduction of steroid treatment. It may be isolated, without clinical feature of arteritis and without an elevated erythrocyte sedimentation rate. This inappropriate anti-diuretic hormone secretion, probably due to ischemic involvement of the pituitary or hypothalamic region, always improves quickly after institution of steroid therapy.