緩下剤の長期乱用による酸性尿酸アンモニウム結石の1例 本邦報告例の検討

Abstract

27歳女性.患者は左背部痛を主訴に前医を受診し, CTにて両側尿管結石による水腎症を指摘され, 左経尿道的尿管砕石術を試みた.しかし, 結石は腎内にpush upされ左尿管ステントの留置となった.今回, 精査および加療を目的に著者らの施設へ入院したところ, 小球性低色素性貧血, 血清K濃度の軽度低下, アルドステロンの分泌亢進, 24時間尿量と尿中Na排泄量の著明な低下を認めた.一方, CTでは右尿管結石による高度水腎症と左上部尿管に4mmの結石を認め, 腎動態シンチでは右腎機能は廃絶し, 機能的左単腎であった.左腎内結石を尿管鏡で摘出したところ, 結石成分は酸性尿酸アンモニウムであった.患者は15歳より体重増加防止の目的で市販の緩下剤を常用しており, そのため, まずはこの緩下剤を中止させ, 精神科医のカウンセリングを行った.その結果, 尿量ならびに尿中Na排泄量は著明な改善を認め, 現在は外来経過観察中で結石再発はなく, 排便も酸化マグネシウムや大建中湯などでコントロールされている

We report a case of ammonium acid urate stone due to laxative abuse. A 27-year-old female complained of left flank pain. Computed tomography revealed bilateral ureter stones (right 16.5 x 9.0 mm; left 4 mm), while left ureter stone was radiolucent on the plain X ray film. Bilateral hydronephrosis was seen, but no therapy was performed for the right stone, because 99mTc-MAG3 scintigraphy revealed that right kidney had no function. The left stone was successfully removed by transurethral approach. The stone was revealed to be an ammonium acid urate by infrared spectrophotometry. She had been taking many laxatives (bisacodyl, sennoside, aloe extract) for 12 years to control her body weight. Ammonium acid urate stones are rarely seen in developed countries. We have reviewed 9 cases in Japan, describing ammonium acid urate stones due to laxative abuse. Among these patients, 24-hour urine volume and excretion in urinary sodium were decreased, and serum aldosterone was increased. The involvement of laxative abuse should be considered when ammonium acid urate is formed in a woman with a low body mass index.