日本未熟児新生児学会雑誌　第21巻　第2号　37～42頁（2009年）

日本未熟児新生児学会雑誌　21(2)：213-218；2009　

受付日：平成20．03．28

受理日：平成20．08．08

生後2週目に急激な溶血性黄疸をきたした超低出生体重児の4例

Sudden Onset of Hemolytic Anemia and Jaundice in Four Extremely Low-birth-weight Infant during Second Week after Birth

国立病院機構佐賀病院　母子医療センター　小児科

Department of Pediatrics, National Hospital Organization, Saga National Hospital

江頭智子・岩永　学・小形　勉・松尾幸司・高柳俊光

Tomoko EGASHIRA, Manabu IWANAGA, Tsutomu OGATA, Koji MATSUO,Toshimitsu TAKAYANAGI

Key Words：溶血，超低出生体重児，メトヘモグロビン，ビタミンK

　急性期を過ぎた生後2週目に，急激な溶血性黄疸をきたした超低出生体重児の4例を報告する。発症日齢は10～14で，いずれも急激なビリルビン値の上昇と貧血の進行を認め，血液ガス分析でメトヘモグロビンとCOヘモグロビンの比率の増加が確認された。いずれも本症状に先行してパルスオキシメーター上，動脈血酸素飽和度の低下を認め，これら異常ヘモグロビンの関与が推測された。いずれも直接抗グロブリン試験は陰性で，明らかな出血病変の合併はない。1例は光線療法のみで管理できたが，残りの3例で交換輸血を余儀なくされた。溶血は一過性でその後の再燃は認めていない。本症の病態生理は不明であるが，超早産児の赤血球膜の未熟な抗酸化能を背景に，高濃度酸素への暴露や，未熟な皮膚のバリア機能，Vit Kに代表される種々の薬物の関与などが複合的に関与している可能性を推測した。また，類似する臨床報告がこれまでも本邦で複数なされており，本症の疫学を明らかにする必要性がある。

　We reported four extremely low-birth-weight infants with the sudden onset of hemolytic anemia and jaundice during the second week after birth. They were born between 24.3wks and 26.4wks after gestation and their birth weight was between 638 and 842 grams. Although intensive care including mechanical ventilation was required soon after birth, they were all well stabilized within the early neonatal period.
　Two or three days before this episode, we noticed the unexplained decline of SpO2 value by pulse oximeter. The elevated percentage of abnormal hemoglobin including met-hemoglobin and CO-hemoglobin has also recognized by the device of blood gas analysis. Hemolytic anemia and jaudice have suddenly developed between 10 and 14 days old. Direct Cooms test was negative, and apparent hemorrhagic lesion was absent in all infants. All were treated with phototherapy and red blood cell transfusion, however, three patients required whole blood exchange. This hemolytic crisis was transient in all patients, and all have resolved within a week.
　The cause of this hemolytic episode is yet obscure, however, in addition to the immature antioxidant function of red blood cell membrane against oxygen radical in extremely low-birth-weight infant, several factor such as receiving high concentration of oxygen, tiny skin itself, and some kind of drug including vitamin K might be concerned.