Abnormalities of the kynurenine (KYN) pathway may be implicated in the pathophysiology of depression. However, the relationships between depression and each metabolite of the KYN pathway remain uncertain. Therefore, we conducted a meta-analysis about the levels of the metabolites of KYN pathway between patients with depression and controls. Out of 899 initial records, we identified 22 articles to form the empirical basis. Seventeen, 10, and 18 studies examined levels of kynurenic acid (KYNA), quinolinic acid (QUIN), and KYN, respectively. KYNA and KYN levels were lower in patients with depression in comparison to controls, while QUIN levels did not differ between the two groups. Antidepressant-free patients showed decreased KYNA levels and increased QUIN levels compared with controls. Male ratios of the samples were negatively associated with study SMDs for KYNA. In conclusion, this meta-analysis revealed that patients with depression had decreased level of KYNA and KYN, whereas antidepressant-free patients showed increased level of QUIN. Nevertheless, given the heterogeneity among their sample characteristics, further research is clearly needed.

犬尿氨酸（KYN）途径的异常可能与抑郁症的病理生理有关。然而，抑郁与KYN途径的每种代谢物之间的关系仍然不确定。因此，我们对抑郁症患者和对照组之间的KYN途径代谢产物的水平进行了荟萃分析。在899笔初始记录中，我们确定了22篇文章作为经验基础。十七项，十项和18项研究分别检查了运动尿酸（KYNA），喹啉酸（QUIN）和KYN的水平。与对照组相比，抑郁症患者的KYNA和KYN水平较低，而两组的QUIN水平没有差异。与对照组相比，无抗抑郁药的患者的KYNA水平降低，QUIN水平升高。样品的男性比例与KYNA的研究SMD呈负相关。总之，这项荟萃分析显示，抑郁症患者的KYNA和KYN水平降低，而无抗抑郁药的患者QUIN水平升高。然而，鉴于样本特征之间的异质性，显然仍需要进一步的研究。