Relationships Between 24-hour LH and Testosterone Concentrations and With Other Pituitary Hormones in Healthy Older Men

Abstract

Objective: To investigate the relationship between LH and testosterone (T), which characteristics associate with the strength of this relationship, and their interrelationships with GH, TSH, cortisol, and ACTH.

Design: Hormones were measured in serum samples collected every 10 minutes during 24 hours from 20 healthy men, comprising 10 offspring of long-lived families and 10 control subjects, with a mean (SD) age of 65.6 (5.3) years. We performed cross-correlation analyses to assess the relative strength between 2 timeseries for all possible time shifts.

Results: Mean (95% CI) maximal correlation was 0.21 (0.10-0.31) at lag time of 60 minutes between LH and total T concentrations. Results were comparable for calculated free, bioavailable, or secretion rates of T. Men with strong LH-T cross-correlations had, compared with men with no cross-correlation, lower fat mass (18.5 [14.9-19.7] vs. 22.3 [18.4-29.4] kg), waist circumference (93.6 [5.7] vs. 103.1 [12.0] cm), high-sensitivity C-reactive protein (0.7 [0.4-1.3] vs. 1.8 [0.8-12.3] mg/L), IL-6 (0.8 [0.6-1.0] vs. 1.2 [0.9-3.0] pg/mL), and 24-hour mean LH (4.3 [2.0] vs. 6.1 [1.5] U/L), and stronger LH-T feedforward synchrony (1.5 [0.3] vs. 1.9 [0.2]). Furthermore, T was positively cross-correlated with TSH (0.32 [0.21-0.43]), cortisol (0.26 [0.19-0.33]), and ACTH (0.26 [0.19-0.32]).

Conclusions: LH is followed by T with a delay of 60 minutes in healthy older men. Men with a strong LH-T relationship had more favorable body composition, inflammatory markers, LH levels, and LH-T feedforward synchrony. We observed positive correlations between T and TSH, cortisol, and ACTH.

Keywords: ageing; cross-correlation; luteinizing hormone; men; pituitary hormones; testosterone.

Figure 1.

Concentration profiles of SHBG and albumin over 24 hours. Serum concentrations of SHBG in nmol/L and albumin in g/L were measured in blood that was sampled during 24 hour with 4-hour intervals for each participant. The individual concentrations profiles are plotted as gray lines. The black line represents the mean per timepoint together with the standard error bars. The asterisk indicates that mean albumin levels at 6:00 pm are significantly higher than levels at 6:00 am (P = 0.02).

Figure 2.

Twenty-four-hour concentration profiles and secretion rates of LH and (free and bioavailable) T from 1 individual. The concentration profiles of LH and testosterone (T), together with the calculated secretion rates, and the calculated concentration profiles of free T and bioavailable T from 1 representative participant are plotted over 24 hour. LH and T concentrations were measured in serum which was sampled every 10 minutes during 24 hour. Secretion rates were calculated using deconvolution analysis and free T and bioavailable T concentrations were calculated using total T, SHBG, and albumin levels.

Figure 3.

Cross-correlations between LH and T. Cross-correlations between LH concentrations and (A) total T concentrations, (B) T secretion rates, (C) free T concentrations, and (D) bioavailable T concentrations in all 20 participants. Cross-correlation assesses the relative strength between 2 hormone time series for all possible time shifts. The graph displays the correlation (y-axis) at a lag time in minutes (x-axis) with each gray line corresponding with 1 participant. The black line indicates the mean correlation for all participants and the 2 dark gray lines indicate the 95% CI. The significance level is indicated by 2 straight dotted lines at correlations –0.18 and +0.18. Negative lag times represent a correlation in which hormone 2 is followed by hormone 1 and positive lag times represent a correlation in which hormone 1 is followed by hormone 2. T, testosterone.

Figure 4.

Cross-correlations between LH and T concentrations with GH, TSH, cortisol, and ACTH concentrations. Results of the cross-correlation analyses between LH concentrations and (A) GH, (B) TSH, (C) cortisol, and (D) ACTH concentrations are plotted, together with the cross-correlations between total T concentrations and (E) GH, (F) TSH, (G) cortisol, and (H) ACTH concentrations. Cross-correlation assesses the relative strength between 2 hormone time series for all possible time shifts. The graph displays the correlation (y-axis) at a lag time in minutes (x-axis) with each gray line corresponding with 1 participant. The black line indicates the mean correlation for all participants and the 2 dark gray lines indicate the 95% CI. The significance level is indicated by 2 straight dotted lines at correlations –0.18 and +0.18. Negative lag times represent a correlation in which hormone 2 is followed by hormone 1 and positive lag times represent a correlation in which hormone 1 is followed by hormone 2. T, testosterone.

Figure 5.

Summary of cross-correlations between LH and T concentrations with GH, TSH, cortisol, and ACTH concentrations. A graphical summary of cross-correlation analyses in all 20 participants. Solid lines represent positive correlations between hormones, which is strongest at lag time 0, so without a delay. Solid arrows represent positive correlations between hormones, which is strongest at a certain lag time, with the arrow directed towards the hormone which is following the leading hormone. The weight of the line/arrow represents the strength of the correlation.