Frequency and Clinical Significance of Low or High Sex Hormone Binding Globulin Levels in Patients Suspected of Harboring Abnormal Testosterone Levels

Purpose: We aim to examine the frequency of low or high sex hormone binding globulin (SHBG) levels and to investigate whether they are associated with comorbidities and hormonal derangements in patients suspected of harboring abnormal testosterone levels. Methods: This was a retrospective study of adult patients who underwent SHBG testing as part of a panel for testosterone at UCLA Health between May and July 2019. Results: A total of 1102 male and 689 female patients underwent SHBG testing; the most common indications of the tests were suspected hypogonadism in male and hyperandrogenism in female patients. Eight male (0.7%, 9.4±1.0 nmol/L) and 66 female patients (9.6%, 21.7±5.2 nmol/L) exhibited low SHBG levels, and 113 male (10.3%, 106.6±29.6 nmol/L) and 118 female (17.1%, 187.1±59.6 nmol/L) patients exhibited high SHBG levels. Patients with low SHBG levels were younger, had higher body mass index, and less commonly receive sex hormone treatments than those with high SHBG levels but they were not different in other assessed clinical parameters. Bioavailable and free testosterone levels were not different in males with low or high SHBG levels but were significantly higher in females with low SHBG levels than in those with high SHBG levels.