Definition, Prevalence, and Risk Factors of Low Sex Hormone-Binding Globulin in US Adults.

CONTEXT: Lower sex hormone-binding globulin (SHBG) is associated with many diseases including cardiovascular disease, cancer, polycystic ovarian syndrome, arthritis, and liver disease. However, the definition of low SHBG and its prevalence in US adults are unknown.

OBJECTIVE: To define low SHBG and to determine its prevalence and risk factors in US adults.

DESIGN, SETTING, AND PARTICIPANTS: This cohort study included adults ≥20 years from the US National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016 who had fasting serum SHBG.

EXPOSURES: NHANES coverage during 2013-2016.

MAIN OUTCOMES MEASURES: Definition, prevalence, and risk factors of low SHBG.

RESULTS: This study included 4093 adults (weighted sample size of 204 789 616) with a mean (SD) age of 47.5 (17.0) years. In a "healthy" reference sub-cohort of 1477 adults, low SHBG was defined as SHBG < 12.3 nmol/L in men < 50 years, <23.5 nmol/L in men ≥ 50 years, <14.5 nmol/L in women < 30 years, and <21.9 nmol/L in women ≥ 30 years. The estimated US national prevalence of low SHBG was 3.3% in men, 2.7% in women, and 3.0% overall. Risk factors for this condition in both men and women included higher body mass index, diabetes, ethnicity (being other than Hispanic, non-Hispanic black, or non-Hispanic white), chronic obstructive pulmonary disease, coronary heart disease, and smoking.

CONCLUSIONS: This study established the criteria for low SHBG among US adults. The estimated US national prevalence of low SHBG was 3.3% in men and 2.7% in women.