Background A subnormal cortisol response (30 min level (C30min)<550 nmol/L) to synthetic adrenocorticotrophic hormone/Synacthen test (SDST) in all infants does not necessarily indicate underlying or persistent hypothalamic–pituitary–adrenal axis pathology.
Methods We retrospectively evaluated the diagnoses and outcomes in 68 infants who had a SDST at age <6 months from 2011 to 2014.
Results 29 (43%) infants had a subnormal SDST. Causative pathology was identified in 9/29 (31%). In 20/29 (69%) with no identified pathology, repeat SDST was normal in 18/20 (90%) at median age 0.6 (range 0.1–3.2) years but persistently subnormal in 2. Those with a transient abnormality were more likely to be small for gestational age (P=0.03) and had higher initial SDST C30min (390 nmol/L vs 181 nmol/L, P=0.01) than those with pathology.
Conclusion Specific aetiology can be identified in a third of infants with a subnormal SDST. When the aetiology remains elusive, adrenal function should be reassessed as the problem can be transient.
- adrenal function
- glucocorticoid deficiency
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Contributors LP initiated the study, designed data collection tools and monitored data collection for the study. She is the guarantor. TSET and CM collected and analysed the data as well as drafted and revised the paper. TSET and CM are joint first authors. RK, JJ, EOS, RP, MS, SE, FI, LT, PEC, IB and LP, who were involved in the clinical care of the infants, critically reviewed and revised the manuscript. All authors contributed to finalising the manuscript as submitted.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data are available upon request.
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