[Hypothalamic hyperosmolarity in childhood (author's transl)]

Hypothalamic lesions occasionally lead to excessive hypernatraemia and hyperosmolarity which cannot be explained by defective ADH secretion alone. As osmoregulation is a complex system the clinical features differ widely from one patient to another. In general central dysregulation of osmolarity is due to diffuse hypothalamic lesions, e.g. inflammatory inflammatory infiltration by histiocytosis X or by large suprasellar tumours. We report on a ten-year-old girl suffering from a suprasellar spongioblastoma and a twelve-year-old-girl, who had been operated for a large craniopharyngioma. Polyuria and polydipsia were not present. Whereas one patient presented hypernatraemic crises and showed normal osmolarity at the intervals, the other patient suffered from sustained hypernatraemia and hyperosmolarity. In the first patient water loading led promptly to clinical and laboratory normalisation. In the other case water loading failed to decrease hyperosmolarity but led to oedema. In the first patient hypernatraemic crises were combined with decreased serum potassium levels and elevated urinary aldosterone excretion. Therefore acute and long-term trials of spironolactone treatment were successful. Exogenous ADH-derivatives failed to normalize hyperosmolarity. In the other patient, however, DDAVP decreased the serum sodium level seen with small doses.