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 30min2,3. 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.
19 Sep 2019 - 21 Sep 2019