SIADH Caused by the Synergistic Effect of S-1 and Thiazide

S-1과 티아지드 상승효과에 의한 항이뇨호르몬과다분비증후군 1예

Hyponatremia is a dangerous electrolyte disturbance in patients on chemotherapy and may cause sudden death if not detected early. SIADH (syndrome of inappropriate antidiuretic hormone) is one of the known causes of hyponatremia in patients undergoing chemotherapy. Few chemotherapeutic agents, however, are reported to cause SIADH. The current study reports that SIADH developed in a 55 year old woman on S-1 ($80\;mg/m^{2}$) and cisplatin ($60\;mg/m^{2}$) chemotherapy for the peritoneal metastasis of gastric cancer. The patient underwent a total gastrectomy, a splenectomy, and a segmental resection of the transverse colon for gastric cancer. She had used thiazide and ${\beta}-blocker$ to treat hyperiension for 12 years. She admitted to our hospital with complaining of general weakness, dysarthria, loss of appetite, and urinary discomfort. The serum level of sodium and potassium were 94 mEq/L and 2.2 mEq/L respectively. The hyponatremia completely resolved uneventfully after 3% saline infusion, which led to normalized electrolyte balance. The patient was discharged on the 13th hospital day.

저나트륨혈증은 항암화학요법 중에 발생하는 전해질 장애 중의 하나이며, 조기에 발견하여 치료하지 않을 경우 급사할 수 있다. 저나트륨혈증을 유발하는 여러 원인중에 항이뇨호르몬과다분비증후군(syndrome of inappropriate antidiuretic hormone, SIADH)이 항암화학요법을 시행받은 환자들에게서 발생하였다고 보고되고 있다. SIADH를 유발하는 항암제는 아직까지 몇 가지 외에는 많이 알려져 있지 않다. 본 예는 위암으로 위전절제술, 비장절제술, 횡행결장구역절제술을 시행 받은 55세 여자로 수술 후 복막전이가 발견되어 S-1 ($80\;mg/m^{2}$)과 cisplatin ($60\;mg/m^{2}$)을 이용한 항암화학요법 중 SIADH가 발생하였다. 환자는 3% 생리식염수를 투여한 후 저나트륨혈증이 정상화되어 퇴원하였다.