A RARE CAUSE OF HYPONATREMIA DURING INDUC TION THERAPY OF ACUTE LYMPHOBLASTIC-LEUKEMIA - INAPPROPRIATE SECRETION OF ATRIAL-NATRIURETIC-FACTOR

Background. - Hyponatremia is frequently seen during the treatment of acute lymphoblastic leukemia: its causes are numerous. This work aims to present a case in whom hyponatremia was possibly due to an increase d secretion of atrial natriuretic factor. Case report. - A 3 week-old baby was admitted because of malignant hemopathy. A diagnosis of acute lymphoblastic leukemia was rapidly made and the patient was firstly g iven alkaline diuresis, urate-oxidase and corticosteroids: Vincristine and daurorubicin were associated one week later. Insertion of a centr al intravenous line in the right subclavicular artery failed so that t his catheter was finally inserted into the left jugular vein. Natremia was 126 mmol/l at that time and dramatically decreased within 24 hour s to 109 mmol/l without net changes in water and electrolytic input. A t that time, sodium urinary excretion was 6 mmol/kg/day (diuresis: 420 ml/day). There was no hemodynamic changes, nor digestive or cardiac m anifestations. Ultrasonography showed that the left superior cava vein drained into the right cardiac atrium. The catheter was withdrawn and the patient was given sodium supplementation permitting complete and definitive cure of hyponatremia within 2 days. Conclusions. - All usua l causes of hyponatremia having been ruled out in this patient, we pos tulate that hyponatrepnia was due to direct stimulation of atrial natr iuretic peptide through an increase in atrial pressure secondary to th e catheter insertion near the cardiac atrium.