Association between serum testosterone changes and parameters of the metabolic syndrome.

Testosterone production is important in males, and various physical and psychological abnormalities occur in individuals with low testosterone levels. In the present study, we aimed to examine the effects of longitudinal changes in total testosterone levels in the same cohort. We included 178 male subjects who visited our hospital multiple times between 2018 and 2023 for medical checkups for at least 3 years. The median baseline age and total testosterone level (TT) of the cohort were 61 years and 4.74 ng/mL, respectively. The patients were divided into four groups based on the difference in TT (ΔTT) between baseline and last visit (Q1, n = 45; Q2, n = 45; Q3, n = 44; Q4, n = 44). ΔTT values ranged from -3.07 to -0.78 ng/mL in Q1, from -0.75 to -0.05 ng/mL in Q2, from -0.03 to 0.73 ng/mL in Q3, and from 0.75 ng/mL to 3.4 ng/mL in Q4. The median ΔTT were -1.22 for Q1, -0.35 for Q2, +0.19 for Q3, and +1.43 for Q4. Decreased TT tended to increase body weight, body mass index, waist circumference, and visceral fat (p for trend 0.0136, 0.0272, 0.0354, and 0.0032, respectively), and decrease adiponectin level (p for trend 0.0219). Herein, we found that decreased TT increases visceral fat and decreases adiponectin levels.