ESPE Abstracts

Objective: Low birthweight (bw) and unfavourable intrauterine conditions have been associated with metabolic and cardiovascular sequelae in later life. Although it is already well known that DHEAS is increased in formerly small-for-gestational-age singletons and in smaller twins compared to their normal-weight co-twin, less is known concerning other adrenal hormones. We analysed diurnal salivary profiles in prepubertal six to eight years old monozygotic twins with intra-twin bw-differences to analyse the long-term impact of bw and catch-up growth on various adrenal hormones.

Methods: 44 monozygotic prepubertal twin-pairs with bw-difference of <1SDS (concordant; n = 28, 13 female) and ≥1SDS (discordant; n = 16, 6 female) were recruited. At a mean age of 6.9 yrs saliva samples were collected (at 7 am/waking, 1 pm, 6 pm, and 9 pm/before bed) and analysed with liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Results: Diurnal salivary concentrations of progesterone, androstendione, 17-OH-progesterone, and testosterone showed statistically significant or highly significant intra-twin correlations in all twin pairs. Graphic evaluation of the diurnal testosterone patterns for each twin pair showed a distinct alignment in all groups. However, the formerly smaller twins showed higher testosterone concentration (1.15 vs 0.4 nmol/L) and higher concentration for progesterone (3.27 vs 0.72 nmol/L) at 7 am. Intra-twin birthweight and intra-twin birth-length correlated significantly to intra-twin testosterone concentration at three of the four time points (correlation coefficient at 7 am: r =0.38; P = 0.04). additionally, intra-twin birthweight and intra-twin birth-length correlated significantly to intra-twin progesterone concentration (correlation coefficient 0.4; P = 0.03) at 1:00 am. Regression analyses of intra-twin differences at 7 am/waking showed a statistically significant influence for auxological birth parameters on testosterone and progesterone. Other time points showed no intra-twin differences.

Conclusion: In monozygotic twins with intra-twin birthweight differences, we found subtle but statistically significant differences regarding testosterone and progesterone. In addition, we found statistically significant intra-twin correlations for all analysed adrenal hormones over the day and a pronounced graphic alignment of diurnal patterns in the individual twin pairs. We therefore suggest an importance of the genetic background with a subtle however remarkable change of some adrenal hormones in correlation to birthweight differences due to different intrauterine conditions. This might have a long-lasting effect and explain metabolic differences later in life.