Evidence check: SHBG in the context of Müdigkeit

SHBG (sex hormone-binding globulin) is a carrier protein for testosterone and estradiol. Low SHBG levels are commonly associated with insulin resistance, metabolic syndrome, obesity, and PCOS – conditions that can indirectly contribute to fatigue. However, the provided context documents contain no direct studies or statements linking SHBG to fatigue. The association rests on mechanistic reasoning (hormone transport, metabolic regulation) and epidemiological correlations, not on specific evidence for fatigue as a symptom. An SHBG test alone cannot diagnose fatigue; it should be interpreted within a broader clinical workup including hormones and metabolic markers. Evidence grade: mechanistic/unclear.