Fig. 4

The role of OP risk factors and thyroid-related hormones as mediators in the causal link between identified TDFDs and OP. (A) Two-step MR analysis structure. β1 denotes the effect of hyperthyroidism on FT4, β2 denotes the effect of FT4 on OP, β3 denotes the effect of hyperthyroidism on OP. (B) Two-step MR analysis structure. β1 denotes the effect of hypothyroidism on TSH, β2 denotes the effect of TSH on OP, β3 denotes the effect of hypothyroidism on OP.