ESPE Abstracts

Introduction: Primary adrenal insufficiency in paediatrics is uncommon but lethal condition, it results most commonly from congenital adrenal hyperplasia¹. Short Synacthen Test (SST) is widely used to assess the glucocorticoid synthesis in the adrenal glands. Synacthen doses are age-based; 62.5mcg for babies younger than 6months, 125mcg for infants between 6-24months and 250mcg for children older than 2years. There is a controversy amongst endocrinologists about the necessity of sampling at 30min^2,3. 0 and 60min samples are claimed to be sufficient for a diagnostic SST result.

Aim: To Report our experience and review the SST protocol in patients investigated for primary adrenal insufficiency with a focus on the concordance between 30 and 60min serum cortisol(SC) measurements.

Methods: All SSTs were performed in our Biochemistry Laboratory were reviewed for paediatric endocrine patients aged below 16 years old between 01/01/2014 to 31/12/2018.The cut off used for SC value is 550 nmol/L.

Results: 53 SSTs (43 patients;F23) were identified via Hospital Information System database and day care unit registry. Mean age and standard deviation were 6±5 years, ranged between 3days and 16years. Out of 53 performed SSTs, only 15 SSTs included the 30min sampling, whereas the rest were done by measuring SC at 0 and 60min. t-test showed difference in the average SC level between 30 and 60min (p 0.0017). The mean SC at 30min was 597nmol/L and 750nmol/L at 60min respectively. In 2 occasions the peak SC was recorded highest at 30min with 6 and 37nmol/L difference in values. Howbeit, it did not lead to change of management should we relied on the 60min reading for those 2occasions. The SC was 48nmol/L for one patient and 684nmol/L for the other i.e. there was clear fail or pass of the SST.

For the rest of performed 38SSTs; sampling was done at only 0 and 60min. There was no dilemma in interpreting results based on their 60min SC readings. It was above 550nmol/L in 24 occasions and below 500nmol/L in other 13 occasions. Only 1 patient had a peak of 512nmol/L which warrant repeating a test to include 30min sampling in case the peak could be higher at this time.

Conclusion: Higher SC levels at 60min compared to 30min was observed; therefore, 30min sampling is not recommended. This may contribute to patient comfort, reducing cost and workload. If peak SC in range of (500-550pmol/L) then consider repeating the SST by including the 30min sampling.