Analysis of diurnal variation in serum testosterone levels in men with symptoms of testosterone deficiency.

Abstract

Testosterone (T) plays a crucial role in various physiological functions in men, and understanding the variations in T levels during the day is essential for diagnosing and treating testosterone deficiency (TD). We sought to evaluate the reduction in serum total T (TT) levels throughout the day in men with symptoms of testosterone deficiency and to determine the variables having an impact on the extent of this decline. The study population consisted of a group of men who within 3months of each other had all undergone both early morning and afternoon TT level measurements. We did not include patients with a history of a prior orchiectomy, testosterone levels below 100ng/dL or above 1000ng/dL, a history of androgen deprivation therapy, or patients on T therapy. Statistical analyses were conducted using descriptive statistics, t-tests, chi-square tests, and correlation calculations. Liquid chromatography-tandem mass spectrometry was used to measure TT, and a change in TT levels greater than 100ng/dL was considered significant. Using multivariable and univariable analysis, we attempted to define predictors of a decrease in afternoon TT levels. The majority of men showed no significant difference in T levels between morning and afternoon. In total, 506 men with a median age of 65years were analyzed. The most common comorbidities were hypertension and hyperlipidemia. Levels of TT were measured in the morning and afternoon, and no significant differences in mean T levels based on the time of the test were found. Age was not significantly associated with T levels. There was a weak negative correlation between age and the difference between morning and afternoon T levels, with younger men showing more significant variations in T levels. The most considerable differences in T levels were observed in men younger than 30 years. There were no predictors of the magnitude of the T decrease in the afternoon. Strengths of the study include the number of subjects and the use of liquid chromatography-tandem mass spectrometry for T measurement. Limitations include failure to measure morning and afternoon T levels on the same day, the retrospective nature of the study, and a smaller sample size of patients younger than 30years. In this study we found no strong link between age and daily T fluctuation, but we observed a decrease in the magnitude of variation with aging. The group experiencing the most significant decline in daily T had higher morning and consistently normal afternoon T levels.