[Hypo-uricemia in the syndrome of inappropriate secretion of antidiuretic hormone: A prospective study].

PURPOSE: Hypo-uricemia is still considered as a hallmark of the syndrome of inappropriate secretion of antidiuretic hormone.

METHODS

We analyzed prospectively 98 hospitalized patients with hyponatremia (≤135 mmol/L), excluding those receiving diuretic treatment. Gold standard for the syndrome of inappropriate secretion of antidiuretic hormone combined plasma hypoosmolality, inappropriately concentrated urine, and normal volemia.

RESULTS

A final diagnosis of inappropriate secretion of antidiuretic hormone was obtained in 55 patients. They were significantly hypo-uricemic (188 μmol/L [153-245], median [interquartile range]) versus 241 μmol/L, [179-333]; p<0,02) but hypo-uricemia (≤240 μmol/L) performed poorly as a diagnostic test: 71 % sensitivity, 53 % specificity. Positive and negative likelihood ratios were 1,67 and 0,49, respectively.

CONCLUSIONS

The syndrome of inappropriate secretion of antidiuretic hormone is associated with a lower plasma uric acid concentration, but in routine clinical practice, contrary to what has been previously published, this difference is insufficient for hypouricemia to discriminate reliably between the syndrome of inappropriate secretion of antidiuretic hormone and other causes of hyponatremia.