Tuberculous lymphadenitis and syndrome of inappropriate antidiuresis, improbable partners.

A patient with acute respiratory infection and severe hyponatraemia was admitted to our department. The hyponatraemia study was compatible with syndrome of inappropriate antidiuresis (SIAD) and an association with the respiratory problem was initially assumed. The recurrence of hyponatraemia after resolution of the pulmonary infection led to further investigation and to the diagnosis of tuberculous lymphadenitis.