Myths vs facts: SHBG and fatigue

SHBG (sex hormone-binding globulin) is a carrier protein for testosterone and estradiol. A common myth is that low SHBG directly causes fatigue. The evidence for a direct causal link is weak. Low SHBG often reflects insulin resistance, obesity, or fatty liver—conditions that themselves are associated with fatigue. High SHBG (e.g., in hyperthyroidism or estrogen dominance) can reduce free androgens, potentially lowering energy. However, research shows SHBG alone is not a reliable fatigue predictor; clinical relevance requires evaluating total/free testosterone, LH, FSH, and thyroid markers. Consumer lab tests that measure SHBG in isolation can be misleading. B-vitamin deficiencies (as promoted in Vitamin B-Komplex Energize) can cause fatigue but do not directly affect SHBG. Bottom line: SHBG is a metabolic/hormonal marker, not a fatigue marker. Persistent fatigue warrants comprehensive workup (hormones, iron, vitamin D, thyroid, sleep).