The present invention provides methods for detecting and/or treating a subject having an aneurysm or at risk for developing an aneurysm. It has been discovered that a key metabolite of the kynurenine (Kyn) pathway, a major route for the metabolism of essential amino acid tryptophan (Trp) into nicotinamide adenine dinucleotide (NAD+), plays a critical role in the formation of aneurysms, for example abdominal aortic aneurysms. In particular, it has been discovered that 3-Hydroxyanthranilic acid (3-HAA), a product of kynureninase (KYNU), plays a causative role in the formation of aneurysms by, for example exerting pro-inflammatory effects on vascular smooth muscle cells. It has further been discovered that elevated levels of 3-HAA are indicative of the presence and/or progression of an aneurysm, and 3-HAA levels correlate with the size (aortic diameter) of the aneurysm.
