Severe polyuria and polydipsia in hyponatremic-hypertensive syndrome associated with Wilms tumor.

The combination of hyponatremia and renovascular hypertension is known as hyponatremic-hypertensive syndrome (HHS) and so rarely described in children but associated with various kinds of occlusions of the renal artery. We describe two children who presented HHS with severe hypokalemia, polyuria, and polydipsia associated with Wilms tumor, which required treatment with an angiotensin-converting enzyme inhibitor before nephrectomy. All HHS signs and symptoms resolved only following surgical resection of the tumor, allowing chemotherapy to be given.