The association among serum growth differentiation factor 15 level and suicidal ideation is dependent on testosterone deficiency in depressive patients

Background: Elevated levels of growth differentiation factor (GDF)-15 and reduced levels of testosterone have been linked to depressive disorder, but whether they are also linked to suicidal ideation in patients with depression is unclear.
Methods: This retrospective study involved 301 patients ≥ 22 years old hospitalized for depression between July 2018 and November 2020 at Renmin Hospital of Wuhan University, of whom 120 had suicidal ideation. Serum levels of GDF-15 and testosterone were compared between patients with or without suicidal ideation.
Results: GDF-15 levels were significantly higher among patients with suicidal ideation than among those without, regardless of whether testosterone levels were above or below the median of 314 ng/dL. In multivariate logistic regression involving all patients, serum GDF-15 level was associated with low testosterone level (P=0.001). Among patients with testosterone < 314 ng/dL, an increase of 1 standard deviation in serum GDF-15 level translated to a 1.3-fold increase in the risk of suicidal ideation (P=0.007). This relationship was not observed in all population or patients with testosterone levels ≥ 314 ng/dL.
Conclusion: High serum GDF-15 level may be associated with an increased risk of suicidal ideation in patients with depression, and this association appears to be partly mediated by low testosterone levels.