The syndrome of inappropriate antidiuretic hormone (ADH) secretion in bronchiolitis

Key words: Bronchiolitis, SIADH, Leukoencephalopathy

The paper describes the case of a three-month-old infant who was hospitalized in our neonatal intensive care unit for respiratory distress, hyporeactivity and feeding difficulties. The RSV test on nasopharyngeal sample showed positive result and at the same time the levels of plasmatic sodium were very low. After correction treatment an improvement of clinical conditions was observed but brain-MRI showed the features of a severe leukoencephalopathy caused by hyponatraemic oedema. SIADH is described to be a possible end-point of severe respiratory syndrome, including bronchiolitis. In course of bronchiolitis SIADH can occur with different mechanisms: directly through the virus invasion of central nervous system and/or indirectly with a cytokine-related damage secondary to infection. The iatrogenic one is the most frequent cause of SIADH during bronchiolitis in patients treated with hypotonic solutions, but in this case no infusion was started before.