The Pharmaceutical Benefit Scheme (PBS) criteria for growth hormone (GH) replacement, somatropin, in Australia have recently been updated to include patients with hypopituitarism affecting multiple axes and low IGF-1, whilst previously dynamic testing such as a glucagon stimulation test (GST) was required. It is expected this should reduce unnecessary GST and allow an evidence-based broader group of patients to qualify for PBS subsidy. This study aimed to quantify the number of patients who undertook GST at an endocrinology facility that would not require this test under current criteria.  

This is a retrospective quantitative audit of patients identified from the endocrine dynamic testing database of the Princess Alexandra Hospital endocrinology department, a quaternary centre in Queensland, Australia. Ninety-two patients who underwent GST between 2019-2025 were included. The primary endpoint was the percentage of patients who underwent a GST who would no longer require this testing based on updated PBS criteria. Secondary endpoints were identification of patients who passed the GST and would now qualify for GH replacement, and to identify a relationship between GH levels during the GST and likelihood of fulfilling the new PBS criteria.  

98.91% of GSTs failed to stimulate GH, thus indicative of GH deficiency. Of these patients, 28.5% would qualify for PBS funded GH replacement under the new criteria (at the time of testing). 38 patients had deficiencies in 3 or more pituitary axes but had an IGF-1 within reference range at the time of the GST. Patients who mounted no GH response during the GST were more likely to fulfil the new PBS criteria than those that mounted some response (48.6%, p=0.002, OR 5.037).  

The updated PBS criteria align to evidence-based international guidelines and successfully identify a population at risk for GH deficiency, thereby reducing the need for GST in specialised outpatient endocrinology departments.