A case-report of a 18 month-old boy (b.w. 13.4 kg), who was admitted because of extreme polydipsia (4500 ml!/day) and polyuria. The examination revealed very low osmolality in the morning urine (52 mOsm/kg) and the serum sodium was at the lower limit (138 mmol/l). The polyuria was due to solute-free diuresis. The standardised test of concentrating capacity (DDAVP-test) showed a mild decrease (778 mOsm/kg). The case history revealed, that the child was addicted to high intake of extreme sweet tea. After the restriction of this beverage, the diuresis decreased to 1000 ml during one week and later the urine osmolality (DDAVP-test) increased to 1072 mOsm/kg. The differential diagnosis and psychogenic aspects of the polyu- ria-polydipsia syndrome are discussed.

        Key words: psychogenic polydipsia - polyuria - solute - free diuresis - extreme sweet tea-formula.