Armenian Patil, Gerona Roy R, Blanc Paul D, Wu Alan H B, Mookherjee Somnath
Division of Clinical Pharmacology, California Poison Control System, San Francisco Division, San Francisco, California, USA.
J Emerg Med. 2012 Jul;43(1):54-7. doi: 10.1016/j.jemermed.2011.06.017. Epub 2011 Oct 5.
Anion gap metabolic acidosis is typically encountered in the emergency department (ED) setting as the result of shock, other endogenous metabolic derangements, or from exogenous toxicants. The differential diagnosis for toxicant-related acidosis (exemplified by common mnemonics) emphasizes acute overdose.
The case we present manifested an anion gap (AG) metabolic acidosis due to a chronic intoxication: acetaminophen (APAP) overuse over a period of weeks. Lactic acidemia did not account for the AG. In this case, chronic APAP overuse, combined with decreased caloric intake and weight loss, was associated with excess 5-oxoproline (pyroglutamic acid), an organic acid accounting for the AG metabolic acidosis. Overproduction of 5-oxoproline is attributed to depleted glutathione stores, leading to perturbation in the γ-glutamyl cycle. The patient was treated with supportive care and with N-acetylcysteine (NAC). By repleting glutathione, NAC may facilitate the resolution of excess 5-oxoproline.
The ED differential diagnosis of AG metabolic acidosis in chronic APAP overuse, especially with concomitant nutritional compromise, should include 5-oxoprolinemia.
阴离子间隙代谢性酸中毒在急诊科较为常见，其病因包括休克、其他内源性代谢紊乱或外源性毒物。毒物相关酸中毒的鉴别诊断（以常见记忆法为例）主要关注急性过量摄入。
我们所呈现的病例显示，由于数周内对乙酰氨基酚（APAP）的慢性过量使用，导致了阴离子间隙（AG）代谢性酸中毒。乳酸血症并非导致AG升高的原因。在此病例中，慢性APAP过量使用，再加上热量摄入减少和体重减轻，与过量的5-氧脯氨酸（焦谷氨酸）有关，5-氧脯氨酸是一种有机酸，可导致AG代谢性酸中毒。5-氧脯氨酸的过量产生归因于谷胱甘肽储备的耗尽，进而导致γ-谷氨酰循环紊乱。该患者接受了支持性治疗和N-乙酰半胱氨酸（NAC）治疗。通过补充谷胱甘肽，NAC可能有助于消除过量的5-氧脯氨酸。
在慢性APAP过量使用，尤其是伴有营养状况不佳的情况下，急诊科对AG代谢性酸中毒的鉴别诊断应包括5-氧脯氨酸血症。
