BackgroundIndividuals with major depressive disorder (MDD) have a high suicide risk. Some evidence suggests that uric acid (UA) may be involved in the pathophysiology of MDD. The purpose of this study was to evaluate whether serum UA levels were associated with suicide risk in MDD patients.MethodsOne hundred four female patients with MDD (52 patients with suicide risk and 52 patients without suicide risk) and 52 healthy individuals were included in this study. The suicide risk was evaluated by Mini International Neuropsychiatric Interview (M.I.N.I.). Fasting serum levels of UA, as well as glucose, lipid and renal function indicators were measured.ResultsSerum UA levels in MDD patients with suicide risk (245.01 ± 55.44 μmol/L) were significantly lower than those in MDD patients without suicide risk (274.17 ± 72.65 μmol/L) (p = 0.017) and healthy controls (271.42 ± 55.25 μmol/L) (p = 0.030). There was no difference in serum UA levels between the MDD patients without suicide risk and healthy controls (p = 0.821). Binary logistic regression analysis revealed a significant relationship between suicide risk and decreased serum UA levels (OR = 0.989, p = 0.010) in MDD patients.ConclusionDecreased serum UA levels were associated with suicide risk in MDD patients. Purinergic system dysfunction may be involved in the neurobiological basis of suicide risk in these patients.