Letter to the Editor: Insight into the nonlinear association between thyroid-stimulating hormone and suicide risk in first-episode major depressive disorder

Figure 2 Conceptual dose-response relationship between thyroid-stimulating hormone and suicide. This graph visualizes the key finding by Deng et al[1], identifying a nonlinear, threshold-based association. Below the critical inflection point of 5.43 µIU/mL, the risk curve remains relatively stable. Once thyroid-stimulating hormone crosses this threshold into the mildly pathologically elevated range, the risk of suicide attempts increases sharply (indicated by the orange upward arrow). This diagram highlights the clinical significance of 5.43 μIU/mL as a primary biological “red flag” and underscores the need for sex-stratified risk models. TSH: Thyroid-stimulating hormone.