Background/aims: Insulin tolerance tests (ITT) are considered gold standard to investigate patients for suspected secondary adrenal insufficiency or growth hormone deficiency. In 2021, the Harmonisation of Endocrine Dynamic Testing – Adult (HEDTA) guidelines were published to assist clinicians in conducting endocrine dynamic tests including ITT. Our aim is to describe testing procedures and adherence to HEDTA guidelines at a tertiary hospital over a three-year testing period.
Methods: We included all non-pregnant patients ≥18 years of age who underwent ITT from 2022 to 2024 at Concord Repatriation General Hospital. Data was collected on patient demographics, testing procedures, indications for testing, and outcomes.
Results: Six patients underwent testing with a median age of 44 years (36 – 54) and 67.7% were female. The indication for testing was secondary adrenal insufficiency in 66.7% (4 of 6) of patients, growth hormone deficiency in 16.7% (1 of 6) and both conditions in 16.7% (1 of 6). Adequate hypoglycaemia of ≤2.2mmol/L, was achieved in 83.3% (5 of 6) of patients with 16.7% (1 of 6) requiring a second dose of insulin to achieve this. Median time to blood glucose nadir, cortisol peak, and growth hormone peak was 32.5, 60 and 60 minutes respectively. Inadequate cortisol or growth hormone responses were seen in 66.7% of tests. Deviations from protocol included variations in timing of blood collection and missing ACTH measurements. There were no adverse events. Hypoglycaemia was treated with both oral glucose solution and intravenous dextrose in 83.3% (5 of 6) of patients and the treatment not documented in the remaining 16.7% (1 of 6).
Conclusion: Despite ITT being gold standard, it is infrequently ordered suggesting potential underutilisation for the assessment of secondary adrenal insufficiency and growth hormone deficiency. Adherence to HEDTA guidelines, particularly regarding the timing of specimen collection, may enhance the clinical utility of ITT.