OBJECTIVETo study the syndrome of inappropriate ADH secretion (SIADH) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and the possible etiology.

METHODSThe clinical manifestation, laboratory examination, treatment and outcome of a patient with refractory anemia with excess blasts after allo-HSCT were presented.

RESULTSHyperacute graft-versus-host disease (GVHD) was developed in the patient after allo-HSCT followed by severe hyponatraemia (lowest serum sodium 103.7 mmol/L), natriuresis, hypo-osmolality of plasma, hyper-osmolality of urine, coma and twitch at day 17 after allo-HSCT. SIADH was diagnosed. The clinical condition was improved after restriction of water and administration of hypertonic saline, but SIADH was not controlled completely. Afterwards, graft failure was developed. Hyperacute GVHD and graft rejection occurred again after the second transplant. The patient died of secondary infection.

CONCLUSIONSIADH after allo-HSCT is a rare fatal acute complication of central nervous system. Numerous transplant-related causes are probably associated with the development of SIADH. Early accurate diagnosis and treatment promptly is of great importance.