Multiple Metabolic Abnormalities in a Patient with the Syndrome of Inappropriate Antidiuresis

The syndrome of inappropriate ADH secretion (SIADH) is a common cause of hyponatremia. However, other metabolic abnormalities have infrequently been described in patients with the syndrome of inappropriate antidiuresis. Here, we describe a female patient with hyponatremia due to SIADH who presented with a cluster of metabolic abnormalities and specifically hypouricemia associated with uricosuria, hypokalemia caused by renal potassium wasting, hypomagnesemia with inappropriate magnesiuria, hypophosphatemia with renal phosphate wasting and inappropriate calciuria. These abnormalities could be partly due to the extracellular volume expansion and were corrected with the water restriction-induced increase in serum sodium levels.