Hyponatremia in a Patient with Chronic Inflammatory Disease

Abstract

A 66-year-old man was admitted with destructive arthropathy, and calcium pyrophosphate dihydrate was demonstrated in the synovial fluid specimen. He was found to have a hyponatremia. The serum sodium concentration was 121 mmol/ι, plasma arginine vasopressin (AVP) 6.6 pmol/ι, and serum interleukin (IL)-6 96 pg/ι. The clinical findings suggest the diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH). However, destructive arthropathy with increased values of C-reactive protein and IL-6 is the only background of SIADH in this patient. We suggest the possibility that IL-6 produced at inflammatory lesions may have stimulated an excessive release of AVP resulting in the hyponatremia and hypochloremia of SIADH.
(Internal Medicine 37: 792-795, 1998)