Why is the European Unifying Recommendation for Treating Syndrome of Inappropriate Antidiuretic Hormone (SIADH) and Cerebral Renal Salt Wasting Not Commonly Recommended in the US.

Hyponatremia in patients with the syndrome of inappropriate antidiuretic hormone (SIADH) and in patients with cerebral renal salt wasting (CRSW) requires radically different treatment. Delay in proper treatment often occurs because the laboratory presentation of both syndromes is identical, and the fact that CRSW is considered very rare. The parameters observed are hyponatremia, hypouricemia with high fractional excretion of uric acid, normal renal, adrenal and thyroid function, concentrated urine with urine osmolality higher than plasma osmolality, and urine sodium concentration often > 30 mmol/L. The treatment of SIADH requires fluid restriction or forced fluid excretion, while the treatment of CRSW requires fluid administration. Delays in treatment may result in serious, possibly fatal complications. A unifying treatment protocol has been developed in Europe but is often ignored in the American literature. The European approach introduces a safer treatment of severe hyponatremia when the physician is confronted with either SIADH or CRSW. It recommends initial treatment with boluses of 3% saline over 20 minutes via a peripheral vein, with modifications of the treatment to increase serum sodium by 5 mEq. over the next 1-2 hours.