Endocrine Abstracts

Syndrome of inappropriate antidiuresis hormone (SIADH) with many disorders of the nervous system have been reported frequently but its association with multiple sclerosis (MS) is extremely rare (only six cases reported in the literature).

A 46 years old woman was admitted to our hospital because of hypersomnolence, confusion and visual disturbances. She presented 6 months before a variety of neurological symptoms suggestive of demyelinating disease without radiological or biochemical confirmation.

GSC on admission was 12/15, clinically euvolemic and hemodinamically stable. Laboratory evaluation showed hyponatremia (Na pl 110 mEq/l), hypoosmolality (Posm 246 mosmol/kg), increased urine osmolality (U osm 663 mosm/kg) and inappropriate natriuresis (Na ur 76 mEq/l). There were no clinical, radiologic or laboratory findings of impaired renal function, thyroid or adrenal disfunction, head injury, lung or neoplasic disease. The diagnosis of MS was made on the basis of radiologic (hyperintense signals in optic chiasm and in the hypothalamus in MRI), clinical (optic neuritis) and biochemical findings (oligoclonal protein bands in CSF). The severe hyponatremia was attributed to SIADH secondary to MS and was treated with water restriction, 2% saline infusion and diuretic drugs. The patient was discharged three weeks later with serum sodium levels and the rest of the laboratory data within normal levels.

In summary, the association of SIADH and MS was not coincidental. The cause might be the demyelinating process in the hypothalamus that produced and abnormal influence in ADH secretion resulting in SIADH.