Introduction. An age-associated increase in serum levels of sex hormone binding globulin (SHBG) is considered to be one of the factors leading to the development of male hypogonadism.
Aim of the study: to study the relationship between the concentration of sex hormone-binding globulin in the blood serum and the age of the man, the level of total and free testosterone.
Materials and methods. A single-center retrospective cross-sectional study was conducted. The results of laboratory tests of 162 male patients aged from 18 to 56 years (median – 34 years) were analyzed. The level of total testosterone and sex hormone binding globulin (SHBG) was determined by chemiluminescent immunoassay. The level of free testosterone was determined by the calculation method according to Vermeullen. Statistical analysis was performed using SPSS Statistics v23.
Results. Correlation analysis did not reveal a significant relationship between age and SHBG levels, as well as between age and total testosterone levels. Serum SHBG concentration showed a significant (p < 0.001) strong positive (r=0.61) correlation with the total level and a significant (p=0.042) but very weak positive (r=0.162) correlation with the level of free testosterone Comparison of free testosterone levels in groups of patients with SHBG levels below 16 nmol/l, from 16 to 69 nmol/l and above 69 nmol/l did not reveal significant differences (p=0.163). All patients with free testosterone levels less than 225 pmol/l have total testosterone levels below 12 nmol/l. Among men with total testosterone less than 12 nmol/L, only 27% had free testosterone levels below 225 pmol/l.
Conclusion. Serum SHBG levels in men 18-56 years old are not significantly associated with age. An increase in serum SHBG concentration in men is accompanied by an increase in the level of total testosterone, but does not have a significant effect on the concentration of free testosterone. Determining the level of SHBG and calculating free testosterone is advisable to carry out in patients with total testosterone levels less than 12 nmol/l, since with total testosterone values more than 12 nmol/l, the concentration of free testosterone always corresponds to normal values, and with total testosterone values less than 12 nmol/l only 27% of patients have a reduced concentration of free testosterone.
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