腹水是腹腔内液体的积聚，通常由多种病因引起，包括门静脉高压和腹膜疾病。甲状腺功能亢进症很少与腹水相关，腹水通常是乳糜性的，并伴有中心静脉压高。我们介绍了一名 57 岁女性甲状腺功能亢进症患者的独特病例，该患者未经治疗，表现为非乳糜性腹水，但没有高静脉压的证据。患者最初表现为左小腿疼痛，随后出现腿部水肿、腹胀和腹泻。一系列诊断测试排除了腹水的常见病因，例如肝硬化、肾功能不全、心力衰竭、感染和恶性肿瘤。腹水的特点是甘油三酯水平低，但没有发现静脉压高的证据。值得注意的是，患者的快速周转蛋白水平降低，表明甲状腺功能亢进导致分解代谢亢进和蛋白质合成不足。开始抗甲状腺治疗后，患者的症状明显改善。总之，本报告强调了甲状腺功能亢进症的一种罕见表现，该表现导致非乳糜性腹水，但没有高静脉压。这强调需要将甲状腺功能亢进纳入不明原因腹水的鉴别诊断中，特别是在没有典型甲状腺功能亢进症状的情况下。版权所有 © 2023，Takahashi 等人。

Ascites is the accumulation of fluid in the abdominal cavity and is commonly attributed to various etiologies, including portal hypertension and peritoneal diseases. Hyperthyroidism is rarely associated with ascites, which is typically chylous and accompanied by high central venous pressure. We present a unique case of a 57-year-old woman with untreated hyperthyroidism who manifested non-chylous ascites without evidence of high venous pressure. Initially presenting with left lower leg pain, the patient presented with leg edema, abdominal distention, and diarrhea. A range of diagnostic tests ruled out common etiologies of ascites, such as liver cirrhosis, renal impairment, heart failure, infection, and malignancy. Ascites was characterized by low triglyceride levels, while no evidence of high venous pressure was found. Notably, the patient showed decreased levels of rapid turnover proteins, suggesting hypercatabolism and insufficient protein synthesis due to hyperthyroidism. Upon the initiation of antithyroid therapy, the patient's symptoms markedly improved. In conclusion, this report highlights a rare manifestation of hyperthyroidism that resulted in non-chylous ascites without high venous pressure. This underscores the need to include hyperthyroidism in the differential diagnosis of unexplained ascites, particularly in cases in which classical hyperthyroid symptoms are absent.Copyright © 2023, Takahashi et al.