BSPED2013 Poster Presentations (1) (89 abstracts)
1Manchester Medical School, The University of Manchester, Manchester, UK; 2Department of Paediatric Endocrinology, Royal Manchester Childrens Hospital, Manchester, UK; 3Department of Clincal Biochemistry, Royal Manchester Childrens Hospital, Manchester, UK; 4Faculty of Human and Medical Sciences, The University of Manchester, Manchester, UK.
Background: The standard dose Synacthen test (SDST) is commonly used to identify glucocorticoid deficiency. A subnormal SDST in young infants raises the possibility of adrenal insufficiency (AI) due to pathology such as congenital adrenal hyperplasia (CAH). A physiological delay in maturation of adrenal glucocorticoid secretion may be another explanation especially in asymptomatic infants with a transiently subnormal SDST.
Aims: To review the diagnoses and outcomes of infants <6 months who had a subnormal SDST at a single regional centre.
Methods: Data from 45 infants <6 months age who had a SDST over a 2-year period was reviewed. A SDST with cortisol level <550 nmol/l at 30 min was defined as subnormal. Hyponatraemia and requirement for fludrocortisone indicated salt wasting AI. Clinical outcomes were reviewed at 6 months after presentation.
Results: The SDST was normal in 23 (51%) and subnormal in 22 (49%) (15 males) infants. Among the latter, the subnormal SDST was associated with hypopituitarism (3/22), 21-hydroxylase CAH (1/22), salt-wasting primary AI of unknown aetiology (1/22), persistent glucocorticoid deficiency necessitating replacement with hydrocortisone but aetiology not identified (9/22, 41%) and transiently impaired SDST (8/22, 36%). Of the eight infants with a transient abnormality, two were born small-for-gestational-age, three were premature and none received steroid treatment antenatally. Their median (range) 30 min cortisol at initial SDST was 416 (266; 431) nmol/l which normalised by age 4 (1; 9) months. They were asymptomatic until follow-up SDST results normalized. No infant presented with an adrenal crisis.
Conclusion: A significant proportion of infants <6 months age have persistent AI, the aetiology of which can be primary, secondary or unascertained. A third of infants are asymptomatic and have a transiently subnormal SDST. This is suggestive of a physiological delay in maturation of adrenal glucocorticoid secretion.