Endocrine Abstracts

Background: Hypocortisolaemia is common in neonates¹ and infants following cardiac surgery.² In critically ill children with other pathologies, hypocortisolaemia may result from accelerated cortisol metabolism and reduced protein binding. However, the timing and frequency of normalisation of cortisol concentrations following infantile critical illness is poorly described.

Objective: To describe the natural history of hypocortisolaemia in critically ill infants admitted to a single paediatric intensive care unit (PICU).

Methods: Retrospective observational study of infants admitted to PICU from 2016–2018. If random cortisol was <450 nmol/l during critical illness a low dose short Synacthen test (LDSST) was performed on recovery. Results were classified based on basal and peak cortisol concentrations: Normal (basal>100 nmol/l, peak >450 nmol/l); suboptimal (basal>100 nmol/l, peak 350–450 nmol/l), abnormal (basal<100 nmol/l, and /or peak <350 nmol/l).

Results: Data from 63 infants (40M, 23F), mean age 2.4 months (range 1 wk to 10 m), were analysed. 30 patients (47.6%) had cardiac malformations, 11 (17.5%) abdominal pathologies, 5 (8.0%) sepsis, 4 (6.3%) brain pathologies, 3 (4.7%) spina bifida, 3 (4.7%) respiratory pathologies and 7 (11.0%) other pathologies. During critical illness random cortisol was <450 nmol/l in 57/63 infants (90%): undetectable in 25 (43.8%); 50–350 nmol/l in 28 (49%), and 350–450 nmol/l in 4 (7%). 49 infants (86%) underwent a LDSST which was normal in 33 infants (67.3%) in whom random cortisol was <50 nmol/l in 23 (47%) and 50–350 nmol/l 10 (20.4%) during critical illness. 15 patients (30%) with abnormal (N=11) or suboptimal (N=4) LDSST were treated with hydrocortisone for < 6 months in 5 patients (33.3%) and > 6 months in 10 patients (66.7%).

Conclusions: Hypocortisolaemia persisted for longer following critical illness than reported previously in other infant cohorts.¹ Greater understanding of the mechanisms of hypocortisolaemia during and following critical illness should enable more accurate prognosis, diagnosis and management.

References

1. Tan et al, Arch Dis Child. 2018. doi: 10.1136/archdischild-2017-313819.

2. Crawford et al., Paediatr Anaesth. 2017;27:77–84.