The adrenal glands sit above the kidneys and are part of the body's endocrine system. They produce a number of different steroid hormones; those involved in metabolism (glucocorticoids, principally cortisol and its more inactive form, cortisone), salt and water balance (aldosterone) and sex steroids (oestrogen and testosterone). Measurement of steroids, in particular glucocorticoids, in saliva rather than blood samples, is gaining popularity as it offers a non-invasive collection technique, enabling sampling in outpatients, the community or the home environment, and therefore an improved patient experience.~Adrenal insufficiency (AI) describes the inability of the body to produce adequate levels of the vital stress hormone, cortisol. It is associated with considerable mortality and morbidity. There are numerous causes, both in adults and children. The commonest cause in children is AI secondary to steroid medication prescribed for inflammatory conditions such as arthritis and asthma. AI is usually permanent but, especially in those patients taking steroid medication, it may not be, and repeated testing may be required. Testing for AI requires measurement of cortisol. Cortisol levels change during the day (highest soon after waking) and increase in response to stress. There is a lack of data on what constitutes a normal cortisol level under different conditions in children, especially babies and very young children. The investigators would like to use salivary glucocorticoid sampling to study normal responses in children, in order to be able to better define what is abnormal, to ensure appropriate and safe management of children at risk of AI in the future. The current salivary collection techniques (SCT) require active patient participation, present a potential choking hazard, and are therefore unsuitable for very young children. The investigators have been working on a SCT suitable for neonates, infants, and toddlers. Our novel SCT uses a salivary steroid swab encased in a pacifier/dummy (SaliPac) and will enable study of normal adrenal gland function at different ages and under different conditions and disease states from which the investigators will construct normal reference ranges. The final step in the validation of the novel SCT is this patient study where usability, patient tolerability and carer acceptability will be examined.
Currently, the only way to analyse glucocorticoids for the screening or diagnosis of AI in young children is via plasma obtained by invasive capillary or venous blood sampling. Thus, there is an unmet need for a safe and simple salivary collection technique for use in children under the age of six years. The development of the SalivaBio offers potential for salivary collection, which is safe, easy and less-invasive than current practice. The SaliPac has been developed to offer a more tolerable and pleasant way of sampling saliva using a SalivaBio in very young children which the investigators envisage being used by parents/carers at home to sample and then post to the hospital for GC analysis.