“…Postoperative hyponatraemia is a frequent and potentially dangerous complication in adults (Ayus et al, 1992), and is usually secondary to inappropriate hypotonic¯uid replacement, though plasma vasopressin concentration may also be increased in the postoperative period (Chung et al, 1986). Irrigation of the bladder with hypotonic glycine solutions during transurethral resection of the prostate can lead to direct absorption of water from the bladder into the venous circulation, producing dilutional hyponatraemia (Osborne et al, 1980). Hypothyroidism is associated with increased total body sodium (Surveyor, 1963), and although hyponatraemia is reported in up to 10% of hypothyroid patients with normal renal function (Montengro et al, 1996), symptomatic hyponatraemia is rarely seen in clinical practice.…”