Pitfalls in SIADH-diagnosed hyponatraemia: Report of two cases.

In the majority of hospitalised patients with hyponatraemia, syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the primary cause. Before considering SIADH, adrenal, thyroid and pituitary insufficiency should be ruled out. However, the evaluation of these contains potential pitfalls which could lead to incorrect diagnosing of SIADH. Here we present two cases in which a suspected SIADH turned out to be caused by hypopituitarism, emphasising the importance of correctly excluding adrenal, thyroid and pituitary insufficiency.