Background: Due to practical limitations, the diagnosis of hypogonadism is predominantly based on a single measure of reproductive hormones, often with confirmation on a second occasion. Factors associated with reproductive hormone variation include: pulsatile secretion, diurnal rhythm, and food intake, which can affect the accuracy of diagnosis of reproductive disorders. There is limited data quantitatively estimating the variability of reproductive hormone levels over the day. Hormonal sampling data collected over several hours allowed quantification of how representative a single morning measure of reproductive hormones (often used for diagnosis in the clinic) is of the daily hormonal profile.
Methods: Data from 13 research studies (including 267 participants) conducted at Imperial College London were used to quantify the variability in reproductive hormones in both healthy men and women (n=142), and those with reproductive disorders (n=125). The impact on hormone levels of pulsatile secretion, diurnal variation, feeding, and overall variability (Coefficient of Variation (CV)) was quantified.
Results: The initial morning value of reproductive hormones was higher than the mean value throughout the day (percentage decrease from morning to daily mean: LH 18.5%, FSH 9.8% and Testosterone 9.6% and Oestradiol 2.7%). FSH was the least variable reproductive hormone (CV 9%), followed by sex-steroids (testosterone 12%, oestradiol 13%), whereas LH was the most variable (CV 28%). In healthy men, testosterone fell between 9am and 5pm by 14.9% (95%CI -4.20%, -25.5%), although morning levels correlated with (and could be predicted from) evening levels in the same individual (r2=0.53, P<0.0001). Testosterone was reduced more following a mixed meal (34.3%) than after an intravenous bolus of glucose (7.4%; P<0.0001).
Discussion: Quantification of the variability of a single measure of reproductive hormones enables more precise estimation of the hormonal profile during the day, with relevance for the diagnosis of hypogonadism and its aetiology.
14 Nov 2022 - 16 Nov 2022