Session: SAT 41-52-HPA Axis & Disease States
Poster Board SAT-44
Insulin induced hypoglycaemia or Insulin Tolerance Test (ITT) is considered the gold standard assessment of the hypothalamic-pituitary-adrenal axis (HPA). Both synthetic adrenocorticotropic hormone (short synacthen test, SST) and glucagon provocation (glucagon stimulation test, GST) are considered as safe and less labour intense alternative to ITT. Much controversy surrounds the accuracy of these two screening tests when compared to ITT with different levels of sensitivities and specificities reported.
As part of ongoing audit we examined the agreement of test results from SST, GST and ITT performed for investigation of clinically suspected HPA axis dysfunction.
Between March 2009 and March 2012 thirty two patients underwent two or more assessment of the HPA axis with SST, GST or ITT. Patients were included in the audit if they had at least two of the three screening tests and their full medical notes could be retrieved. The agreement between the three tests results were evaluated using Cohen’s Kappa coefficient.
32 patients underwent ITT of whom 31 had pre-screening SST and/or GST. Twenty one were females and average age was 42.9.
26 patients underwent both SST and ITT, 16 patients underwent GST and ITT, and 13 had SST and GST.
Calculated kappa coefficient between tests for SST and ITT were 0.013 (95%CI -0.143 to 0.168), -0.250 (95% CI -0.250 to 0.145) for GST and ITT, and 0.130 (95% CI -0.130 to 0.403) for SST and GST.
Taking Kappa threshold of < 0.40 or even <0.20 to indicate poor agreement, our audit data show poor or no agreement between the three tests used for HPA axis assessment. Most importantly our results indicate no agreement between SST/GST and the gold standard ITT.
In patients with relative or absolute contraindication to ITT, pre-tests probability and clinical assessment should form an integral part of interpreting SST and GST results when used in the evaluation of the HPA axis.
Nothing to Disclose: RJB, ISE, MAAM
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