RESUMO
A child with neonatal pseudohypoaldosteronism is referred. The diagnosis was delayed and complicated as her parents didn't tell us that her sister had been affected by the same illness. The child was born after premature rupture of membranes at 34 weeks. At birth, her conditions were satisfactory. The general conditions of the child gradually worsened and, though she regularly ate human pastorized bank milk, she didn't gain any weight. After 13 days she appeared dehydrated with marbled dry skin and haloed eyes, hypotonic and hyporeflexic. Her suction became more and more weaker, with frequent regurgitations and vomiting. Laboratory tests pointed out hyponatremia (110 mEq/l) and hyperkalemia (6.8 mEq/l). We were able to establish diagnosis of primary pseudohypoaldosteronism measuring plasma concentrations of aldosterone (> 5000 pg/ml), 17 hydroxyprogesterone (normal) and corticosteroids (normal). The child was then supplemented with sodium chlorure. A gradual improvement of general conditions took place. We assumed that both childrens and mother were affected by a milder form of primary pseudohypoaldosteronism, characterized by an autosomal dominant way of transmission. We found high levels of aldosterone with normal levels of blood salts also in the sister and mother patient's. After the neonatal period, pseudohypoaldosteronism can be only suspected in case of positive family history.