Evidence check: SHBG in the context of fertility

SHBG (sex hormone-binding globulin) binds sex hormones, thereby affecting free testosterone and estradiol levels. In fertility contexts, SHBG is often discussed in relation to PCOS, insulin resistance, and thyroid function. Low SHBG may indicate elevated androgen levels that can disrupt ovulation. High SHBG can occur in hyperthyroidism or liver disease. Consumer DNA tests offer SHBG gene variants (e.g., rs1799941), but evidence for clinical utility in fertility optimization is weak. Most studies show only moderate associations, not causal effects. Clinically, direct blood measurement of SHBG is more relevant. Caveat: No specific data from the provided context. Evidence: unclear.