Elucidating and modelling complex postnatal steroid hormone changes in preterm infants: insights into the developing immature neonatal adrenal cortex

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This study will use mathematical models to find out how hormones produced by the adrenal gland in premature babies change after birth. The adrenal glands sit on top of the kidneys. They are part of the endocrine system, which organises the release of hormones within the body. Hormones are chemical messengers that switch on and off processes in the body. The adrenal produces several steroid hormones, which are important for a number of adaptations to life including a stress response, blood sugar regulation, and blood pressure control. Many preterm (born before 37 weeks' gestation) and term babies have problems with blood sugar and blood pressure. Cortisol is an important a steroid hormone that is part of a stress response and helps to maintain blood sugar. We can give a steroid medicine called hydrocortisone if we are concerned that a baby may not be making enough cortisol. Without the right treatment a baby can become very sick. However not all babies need extra steroid medicine but it can be hard to predict which do and which do not. One big problem is that in premature babies, normal reference ranges for many hormones do not exist. A reference range is the range of values that is deemed normal for a physiological measurement in a healthy person. In this study, measurements of blood and urine concentrations of cortisol and other important steroid hormones produced by the adrenal gland will be taken. The main outcome is to find a model that describes the measurements in a way that relates to biological processes. Mathematical models are descriptions of measurements using a system of equations. Investigating which parts of the model differ between babies born at different gestational ages will help to create normal reference ranges for important adrenal hormones and allow correct interpretation of results. With advances in the neonatal care of these preterm babies, and their survival to term, there is a growing need for normative data to support their clinical outcomes. Without such data, these babies may receive inappropriate long-term treatment with steroids. This can lead to serious health-risks such as weight gain, reduced bone strength, slow growth, high blood pressure, high blood sugar and increased susceptibility to infection. This study is a way of gaining knowledge and improving our understanding of the normal adrenal endocrine system of preterm babies in order to improve the standards and quality of care we provide. A secondary objective of this study is the development of a unique bio-resource of anonymised neonatal samples from babies. Any unused material from this study would be deposited in this resource with consent. Full ethical approval would be sought for this bio-resource, and it would be carefully regulated in terms of storage of samples. Every effort will be made to ensure that optimal use is made of donated samples, both in terms of the aims and quality of the research for which it is used and avoidance of duplication/wastage. The bio-resource would also provide opportunity for retrospective studies, and by going back to stored samples and data, the long-term quality of life and clinical outcomes could be improved for generations to come.