International Journal of Clinical Research

Objective To explore the association between subclinical hypothyroidism (TSH 4.5–10 mIU/L) and the severity of depression in patients with depression. Methods A total of 62 patients with psychiatric disorders were included in the study. Their T3, FT3, and other indicators were measured to analyze the relationship between hypothyroidism (TSH 4.5–10 mIU/L) and the severity of depression. Results ① Baseline data: The duration of depression [(3.8±1.5) years] and the rate of antidepressant use (71.43%, 20/28) in the SCH group showed no significant difference compared to the normal group [(2.5±1.2) years, 52.94%, 18/34] (P>0.05). However, the age of the SCH group [(45.2±8.6) years] was slightly higher than that of the normal group [(39.5±7.8) years] (P=0.018); ② Thyroid function indicators: The FT3 level [(3.2±0.4) pmol/L] in the SCH group was significantly lower than that in the normal group [(3.6±0.5) pmol/L] (t=3.852, P<0.001), while TSH was significantly higher than in the normal group (P<0.001). No significant differences were observed in FT4, T3, or T4 (P>0.05); ③ Severity of depression: The HAMD-24 score [(26.8±4.5) points] in the SCH group was significantly higher than that in the normal group [(20.5±3.8) points] (t=6.258, P<0.001). The proportion of severe depression (53.57%, 15/28) was significantly higher than in the normal group (20.59%, 7/34) (χ²=8.652, P=0.003); ④ Correlation analysis: Spearman analysis revealed a positive correlation between TSH levels and HAMD-24 scores (r=0.528, P<0.001), while FT3 levels showed a negative correlation with HAMD-24 scores (r=-0.385, P=0.002). After multivariate linear regression adjusted for confounding factors such as age and gender, TSH remained an independent influencing factor for HAMD-24 scores (β=0.482, P<0.001). Conclusion Subclinical hypothyroidism (TSH 4.5–10 mIU/L) is significantly associated with the severity of depression in patients with depressive disorders. Elevated TSH levels and decreased FT3 levels may be linked to worsening depressive symptoms. Clinically, routine thyroid function monitoring is recommended for patients with depression, and individualized intervention plans should be developed for those with high TSH levels.

Depression; Subclinical hypothyroidism; Thyroid-stimulating hormone (TSH); Severity of depression